Systems and associated methods for producing a 3D sonar image

ABSTRACT

Provided are a sonar system and transducer assembly for producing a 3D image of an underwater environment. The sonar system may include a housing mountable to a watercraft having a transmit transducer that may transmit sonar pulses into the water. The system may include at least one sidescan transducer array in the housing that receives first and second sonar returns with first and second transducer elements and converts the first and second returns into first and second sonar return data. A sonar signal processor may then generate a 3D mesh data using the first and second sonar return data and at least a predetermined distance between the transducer elements. An associated method of using the sonar system is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to U.S.Provisional Application No. 62/128,635, which is entitled “Systems andAssociated Methods for Producing a 3D Sonar Image” and was filed Mar. 5,2015, which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to sonar systemsand, more particularly, to sonar systems, assemblies, and associatedmethods for producing a 3D image of an underwater environment.

BACKGROUND OF THE INVENTION

Sonar (SOund Navigation And Ranging) has long been used to detectwaterborne or underwater objects. For example, sonar devices may be usedto determine depth and bottom topography, detect fish, locate wreckage,etc. In this regard, due to the extreme limits to visibility underwater,sonar is typically the most accurate way to locate objects underwater.Sonar transducer elements, or simply transducers, may convert electricalenergy into sound or vibrations at a particular frequency. A sonar soundbeam is transmitted into and through the water and is reflected fromobjects it encounters. The transducer may receive the reflected sound(the “sonar returns”) and convert the sound energy into electricalenergy. Based on the known speed of sound, it is possible to determinethe distance to and/or location of the waterborne or underwater objects.The sonar return signals can also be processed to be displayed ingraphical form on a display device, giving the user a “picture” or imageof the underwater environment. The signal processor and display may bepart of a unit known as a “sonar head” that is connected by a wire tothe transducer mounted remotely from the sonar head. Alternatively, thesonar transducer may be an accessory for an integrated marineelectronics system offering other features such as GPS, radar, etc.

Traditionally, sonar systems transmit sonar signals into an underwaterenvironment and receive sonar returns that are reflected off objects inthe underwater environment (e.g., fish, structure, sea floor bottom,etc.). Applicant has identified a number of deficiencies and problemsassociated with conventional sonar systems and other associated systems.Through applied effort, ingenuity, and innovation, many of theseidentified problems have been solved by developing solutions that areincluded in embodiments of the present invention, many examples of whichare described in detail herein.

BRIEF SUMMARY OF THE INVENTION

In general, embodiments of the present invention provided herein includesonar systems, transducer assemblies, methods, and associated methodsand systems for producing a 3D sonar image.

In some embodiments a sonar system is provided having a housingmountable to a watercraft capable of traversing a body of water. Thesonar system may include a transmit transducer element positioned withinthe housing and configured to transmit sonar pulses into the water. Insome embodiments the sonar system may include at least one sidescantransducer array positioned within the housing and aimed downwardly andoutwardly from a side of the watercraft. The sidescan transducer arraymay comprise a first sidescan transducer element and a second sidescantransducer element. The first sidescan transducer element may beconfigured to receive first sonar returns from the sonar pulses producedby the transmit transducer element and convert sound energy of the firstsonar returns into first sonar return data. The second sidescantransducer element may be configured to receive second sonar returnsfrom the sonar pulses produced by the transmit transducer element andconvert sound energy of the second sonar returns into second sonarreturn data. The first sidescan transducer element may be positionedwithin the housing at a predetermined distance from the second sidescantransducer element. In some embodiments the sonar system may furthercomprise a sonar signal processor configured to process the first sonarreturn data and the second sonar return data to generate 3D mesh databased on at least the predetermined distance between the first sidescantransducer element and the second sidescan transducer element.

The sonar system may include a display configured to display a 3D imageof an underwater environment based at least on the 3D mesh data.

In some embodiments, the sonar signal processor may be furtherconfigured to process the first sonar return data and the second sonarreturn data to generate a set of 2D sonar data based on thepredetermined distance between the first sidescan transducer element andthe second sidescan transducer element, and may be configured togenerate the 3D mesh data based on the set of 2D sonar data.

In some embodiments, the sonar signal processor may be furtherconfigured to generate a plurality of sets of 2D sonar data as thewatercraft traverses the body of water; and may be configured togenerate the 3D mesh data based on the plurality of sets of 2D sonardata generated as the watercraft traverses the body of water.

In some embodiments, the set of 2D sonar data may define an angleassociated with each sonar return within the set of 2D sonar data. Theangle associated with each sonar return may be based on thepredetermined distance between the first sidescan transducer element andthe second sidescan transducer element. The set of 2D sonar data mayfurther define a strength value and a distance value associated witheach sonar return within the set of 2D sonar data.

The sonar signal processor may be further configured to process thefirst sonar return data and the second sonar return data to generate 2Dsonar data by calculating a phase difference between the first sonarreturn data and the second sonar return data.

In some embodiments, the sidescan transducer array may be a firstsidescan transducer array and the side of the watercraft is a first sideof the watercraft. The sonar system may further comprise a secondsidescan transducer array positioned within the housing and aimeddownwardly and outwardly from a second side of the watercraft. Thesecond side of the watercraft may be generally opposite to the firstside of the watercraft. The second sidescan transducer array maycomprise a third sidescan transducer element and a fourth sidescantransducer element. The third sidescan transducer element may beconfigured to receive third sonar returns from the sonar pulses producedby the transmit transducer element and convert sound energy of the thirdsonar returns into third sonar return data. The fourth sidescantransducer element may be configured to receive fourth sonar returnsfrom the sonar pulses produced by the transmit transducer element andconvert sound energy of the fourth sonar returns into fourth sonarreturn data. The third sidescan transducer element may be positionedwithin the housing at a predetermined distance from the fourth sidescantransducer element. The sonar signal processor may be further configuredto process the third sonar return data and the fourth sonar return datato generate the 3D mesh data based on at least the second predetermineddistance between the third sidescan transducer element and the fourthsidescan transducer element.

In some embodiments, the predetermined distance between the firstsidescan transducer element and the second sidescan transducer elementmay define a first predetermined distance. The sidescan transducer arraymay further comprise a third sidescan transducer element. The thirdsidescan transducer element may be configured to receive third sonarreturns from the sonar pulses produced by the transmit transducerelement and convert sound energy of the third sonar returns into thirdsonar return data. The third sidescan transducer element may bepositioned a second predetermined distance from the second transducerelement. The sonar signal processor may be further configured to processthe first sonar return data, the second sonar return data, and the thirdsonar return data to generate the 3D mesh data based on at least thefirst predetermined distance and the second predetermined distance.

The first predetermined distance between the first sidescan transducerelement and the second sidescan transducer element may be different thanthe second predetermined distance between the second sidescan transducerelement and the third sidescan transducer element. The third sidescantransducer element may be positioned a third predetermined distance awayfrom the first sidescan transducer element. The sonar signal processormay be configured to process the first sonar return data, the secondsonar return data, and the third sonar return data to generate the 3Dmesh data further based on the third predetermined distance.

In some embodiments, the sidescan transducer array may comprise a fourthsidescan transducer element electrically connected in parallel to thethird transducer element such that the third sidescan transducer elementand the fourth sidescan transducer element are configured to receive thethird sonar returns together from the sonar pulses produced by thetransmit transducer element and convert the sound energy of the thirdsonar returns into the third sonar return data.

In some embodiments, the predetermined distance may be designed based ona frequency of operation of the first sidescan transducer element andsecond sidescan transducer element.

The first sidescan transducer element and the second sidescan transducerelement may be configured to receive the first sonar returns and thesecond sonar returns simultaneously.

In some embodiments, the sidescan transducer array may define anemitting surface that corresponds to an emitting surface of the firstsidescan transducer element and an emitting surface of the secondsidescan transducer element. The emitting surface may be straight suchthat the emitting surface of the first sidescan transducer element andthe emitting surface of the second sidescan transducer element may beconfigured to define the same angle with respect to the surface of thebody of water. In some embodiments, the emitting surface of the sidescantransducer array may be angled downwardly and outwardly from thewatercraft and substantially perpendicular to a direction of travel ofthe watercraft.

In some embodiments, the sidescan transducer array may define anemitting surface that corresponds to an emitting surface of the firstsidescan transducer element and an emitting surface of the secondsidescan transducer element. The emitting surface may be curved suchthat the emitting surface of the first sidescan transducer element andthe emitting surface of the second sidescan transducer element may beconfigured to define different angles with respect to the surface of thebody of water.

The sonar system may further comprise shielding positioned in thehousing and configured to surround at least a portion of the sidescantransducer array. In some embodiments, the shielding may compriseabsorption material that defines at least two mounting slots. A firstmounting slot may be configured to surround three sides and two ends ofthe first sidescan transducer element. A second mounting slot may beconfigured to surround three sides and two ends of the second sidescantransducer element.

In some embodiments, the transmit transducer element may be configuredto emit a fan-shaped sonar beam having a relatively narrow beamwidth ina direction parallel to a fore-to-aft direction of the watercraft and arelatively wide beamwidth in a direction perpendicular to thefore-to-aft direction of the watercraft.

In some embodiments, the first sidescan transducer element may be formedof a plurality of transducer elements electrically connected to act asthe first sidescan transducer element.

The transmit transducer element may comprise a linear downscantransducer element positioned within the housing and configured totransmit the sonar pulses in the form of a fan-shaped beam in at least adirection substantially perpendicular to a plane corresponding to thesurface of the body of water. The linear downscan transducer element maybe formed of a plurality of transducer elements electrically connectedto act as the linear downscan transducer element. The linear downscantransducer element may be further configured to receive linear downscansonar returns from the sonar pulses produced by the linear downscantransducer element and convert sound energy of the linear downscan sonarreturns into linear downscan sonar return data. The sonar signalprocessor may be further configured to process the linear downscan sonarreturn data to generate linear downscan image data. Some embodiments ofthe sonar system may comprise a display configured to display a lineardownscan image of the underwater environment based on the lineardownscan image data. In some embodiments, the display is configured todisplay the 3D image of the underwater environment based on the 3D meshdata and the linear downscan image of the underwater environment in asplit screen format.

In some embodiments, the first sidescan transducer element may beconfigured to transmit sonar pulses in the form of a fan-shaped beamdownwardly and outwardly from the side of the watercraft. At least oneof the first sidescan transducer element or the second sidescantransducer element may be configured to receive sidescan sonar returnsfrom the sonar pulses produced by the first sidescan transducer elementand convert sound energy of the sidescan sonar returns into sidescansonar return data. In some embodiments, the sonar signal processor maybe further configured to process the sidescan sonar return data togenerate sidescan image data. The sonar system may further comprise adisplay configured to display a sidescan image of the underwaterenvironment based on the sidescan image data. The display may beconfigured to display the 3D image of the underwater environment basedon the 3D mesh data and the sidescan image of the underwater environmentin a split screen format.

In some embodiments, the sonar system may comprise a circular downscantransducer element positioned within the housing and configured totransmit sonar pulses in the form of a conical-shaped beam in at leastthe direction substantially perpendicular to the plane corresponding tothe surface of the body of water. The circular downscan transducerelement may be further configured to receive conical downscan sonarreturns from the sonar pulses produced by the circular downscantransducer element and convert sound energy of the conical downscansonar returns into conical downscan sonar return data. The sonar signalprocessor may be further configured to process the conical downscansonar return data to generate conical downscan image data. The sonarsystem may further include a display configured to display a conicaldownscan image of the underwater environment based on the conicaldownscan image data. The display may be configured to display the 3Dimage of the underwater environment based on the 3D mesh data and theconical downscan image of the underwater environment in a split screenformat.

In some embodiments the sonar system may further comprise a displayconfigured to display the 3D image of the underwater environment basedon the 3D mesh data and chart information in a split screen format.

In some other embodiments, transducer assembly or method embodiments maybe provided. For example, a transducer assembly may be provided thatcomprises a housing mountable to a watercraft capable of traversing asurface of a body of water. The transducer assembly may include atransmit transducer element positioned within the housing and configuredto transmit sonar pulses into the water. The transducer assembly mayfurther include at least one sidescan transducer array positioned withinthe housing and aimed downwardly and outwardly from a side of thewatercraft. The sidescan transducer array may comprise a first sidescantransducer element and a second sidescan transducer element. The firstsidescan transducer element may be configured to receive first sonarreturns from the sonar pulses produced by the transmit transducerelement and convert sound energy of the first sonar returns into firstsonar return data. The second sidescan transducer element may beconfigured to receive second sonar returns from the sonar pulsesproduced by the transmit transducer element and convert sound energy ofthe second sonar returns into second sonar return data. The firstsidescan transducer element may be positioned within the housing at apredetermined distance from the second sidescan transducer element. Thefirst and second transducer elements may be configured to transmit thefirst sonar return data and the second sonar return data, respectively,to a sonar signal processor to be processed by the sonar signalprocessor to generate 3D mesh data based on at least the predetermineddistance between the first sidescan transducer element and the secondsidescan transducer element.

In some other embodiments, for example, a method for imaging anunderwater environment may be provided. The method may includetransmitting sonar pulses into a body of water using a transmittransducer element positioned within a housing mountable to a watercraftcapable of traversing a surface of the body of water. Embodiments of themethod may include receiving, via a first sidescan transducer element ofa sidescan transducer array, first sonar returns from the sonar pulsesproduced by the transmit transducer element. The sidescan transducerarray may be positioned within the housing and aimed downwardly andoutwardly from a side of the watercraft. The first sidescan transducerelement may be configured to convert sound energy of the first sonarreturns into first sonar return data. The method may include receiving,via a second sidescan transducer element of the sidescan transducerarray, second sonar returns from the sonar pulses produced by thetransmit transducer element. The second sidescan transducer element maybe configured to convert sound energy of the second sonar returns intosecond sonar return data. The first sidescan transducer element may bepositioned within the housing at a predetermined distance from thesecond sidescan transducer element. Some embodiments of the methodinclude processing, via a sonar signal processor, the first sonar returndata and the second sonar return data to generate 3D mesh data based onat least the predetermined distance between the first sidescantransducer element and the second sidescan transducer element.

In yet another embodiment, a sonar system may be provided that includesa housing mountable to a watercraft capable of traversing a surface of abody of water. The sonar system may include at least one sidescantransducer array positioned within the housing and aimed downwardly andoutwardly from a side of the watercraft. The sidescan transducer arraymay comprise a first sidescan transducer element and a second sidescantransducer element. The first sidescan transducer element may beconfigured to transmit sonar pulses into the water, receive first sonarreturns from the sonar pulses produced by the first sidescan transducerelement, and convert sound energy of the first sonar returns into firstsonar return data. The second sidescan transducer element may beconfigured to receive second sonar returns from the sonar pulsesproduced by the first sidescan transducer element and convert soundenergy of the second sonar returns into second sonar return data. Thefirst sidescan transducer element may be positioned within the housingat a predetermined distance from the second sidescan transducer element.The sonar system may include a sonar signal processor configured toprocess the first sonar return data and the second sonar return data togenerate 3D mesh data based on at least the predetermined distancebetween the first sidescan transducer element and the second sidescantransducer element.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 shows a diagram illustrating an example of a sonar transduceremitting sonar pulses from a boat;

FIG. 2 shows a basic block diagram illustrating a sonar system inaccordance with some embodiments discussed herein;

FIG. 3A shows another basic block diagram illustrating a sonar system inaccordance with some embodiments discussed herein;

FIG. 3B shows another basic block diagram illustrating a sonar system inaccordance with some embodiments discussed herein;

FIG. 3C shows another basic block diagram illustrating a sonar system inaccordance with some embodiments discussed herein;

FIG. 3D shows another basic block diagram illustrating a sonar system inaccordance with some embodiments discussed herein;

FIG. 4 shows a basic block diagram illustrating multiple sonar systemsconnected to a network in accordance with some embodiments discussedherein;

FIG. 5A shows a side view illustrating a beam pattern produced by thetransducer assembly according to some embodiments discussed herein;

FIG. 5B shows a top view illustrating a beam pattern produced by thetransducer assembly according to some embodiments discussed herein;

FIG. 6 shows a diagram illustrating a cross section of a transducerassembly according to some embodiments discussed herein;

FIG. 7 shows an example simplified transducer array receiving returnsfrom a floor of a body of water according to some embodiments discussedherein;

FIG. 8 shows the transducer array of FIG. 7 having illustrated wavesbeing received by the transducer elements according to some embodimentsdiscussed herein;

FIG. 9 shows a linear transposition of the two waves of FIG. 8 accordingto some embodiments discussed herein;

FIG. 10 shows a diagram illustrating a cross section of a transducerarray according to some embodiments discussed herein;

FIGS. 11A-11B show diagrams illustrating a cross section of anothertransducer array according to some embodiments discussed herein;

FIG. 12 shows another cross section of a transducer assembly accordingto some embodiments discussed herein;

FIG. 13 shows yet another cross section of a transducer assemblyaccording to some embodiments discussed herein;

FIG. 14 shows a perspective cross section of a transducer assemblyaccording to some embodiments discussed herein;

FIG. 15 shows a cross section of a transducer assembly illustratingexample beam coverage according to some embodiments discussed herein;

FIG. 16 shows another cross section of a transducer assemblyillustrating example beam coverage according to some embodimentsdiscussed herein;

FIG. 17 shows another cross section of a transducer assembly having adownscan transducer array according to some embodiments discussedherein;

FIG. 18 shows yet another cross section of a transducer assemblyaccording to some embodiments discussed herein;

FIG. 19 shows a forward-looking transducer assembly according to someembodiments discussed herein;

FIG. 20 shows an example illustration of a 2D slice having point cloudsrepresenting sonar returns according to some embodiments discussedherein;

FIG. 21 shows a 3D perspective view of a simplified 3D image accordingto some embodiments discussed herein;

FIG. 22 shows a smoothed view of the 3D image of FIG. 21 according tosome embodiments discussed herein;

FIG. 23 shows a waterfall view of a sidescan sonar image according tosome embodiments discussed herein;

FIG. 24 shows a waterfall view of a sidescan sonar image illustrating awatercraft turn according to some embodiments discussed herein;

FIG. 25 shows a side-by-side comparison of images produced by a lineardownscan transducer according to some embodiments discussed herein and aconical downscan transducer according to some embodiments discussedherein;

FIG. 26 shows an example output of a sidescan image overlaid onto 3Dmesh data to form a 3D image according to some embodiments discussedherein;

FIG. 27 shows an example of a 3D image and sidescan image displayed in asplit screen format according to some embodiments discussed herein;

FIG. 28 shows an example of a 3D image and a downscan image displayed ina split screen format according to some embodiments discussed herein;

FIG. 29 illustrates an example method of operating an example sonarsystem, according to some embodiments discussed herein;

FIG. 30 illustrates another example method of operating an example sonarsystem, according to some embodiments discussed herein;

FIG. 31 illustrates yet another example method of operating an examplesonar system, according to some embodiments discussed herein; and

FIG. 32 illustrates an example method of updating a Stored 3D Mesh Dataaccording to some embodiments discussed herein.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention now will be describedmore fully hereinafter with reference to the accompanying drawings, inwhich some, but not all embodiments of the invention are shown. Indeed,the invention may be embodied in many different forms and should not beconstrued as limited to the exemplary embodiments set forth herein;rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals refer tolike elements throughout.

Sonar systems, such as sonar depth finders, sidescan sonars, downscansonars, and sonar fish finders, are commonly employed by boaters, sportfishermen, search and rescue personnel, researchers, surveyors, andothers. With reference to FIG. 1, a boat 10 may include a sonar systemconfigured to create electrical pulses from a transceiver. A transducerthen converts the electrical pulse into sound waves 12, which are sentinto the water. In the depicted embodiment, a fan-shaped sound beam(e.g., a beam shape created from one or more linear transducers) isbeing transmitted into the water, however, as will be apparent to one ofordinary skill in the art in view of this disclosure, other sound beamconfigurations (e.g., conical shaped, elliptical shaped, multipleconical shaped, etc.) may be transmitted.

When the sound waves 12 strike anything of differing acoustic impedance(e.g., the sea floor or something suspended in the water above thebottom), the sound waves 12 reflect off that object. These echoes orsonar returns may strike the transducer or a separate receiver element,which converts the echoes back into an electrical signal which isprocessed by a processor (e.g., sonar signal processor 32 shown in FIG.2) and sent to a display (e.g., an LCD) mounted in the cabin or otherconvenient location in the boat. This process is often called“sounding”. Since the speed of sound in water may be determined by theproperties of the water (approximately 4800 feet per second in freshwater), the time lapse between the transmitted signal and the receivedechoes can be measured and the distance to the objects determined. Thisprocess repeats itself many times per second. The results of manysoundings are used to build a picture on the display of the underwaterenvironment.

For example, the sound waves 12 may bounce off the floor 14 of the bodyof water, an object in the body of water, or another surface in thewater, and reflect back to the boat, thereby indicating the distance tothe reflective surface in the water at that location. Sometimes, thefloor 14 may have an uneven topography (e.g., a raised surface 16) ormay have various objects projecting upwardly or suspended in the watercolumn (e.g., trees or fish) that may reflect different depths of thewater at different locations. In such a circumstance, the sound waves 12reflect off the various floor surfaces and back to the boat 10. If theraised surface 16 is closer to the boat 10, the sound waves 12 willreach the boat 10 faster and the sonar system will calculate that thedepth is shallower at raised surface 16 than at surface 14.Additionally, objects on the floor (e.g., sunken logs, rocks, wreckageof ships, etc.) reflect the sonar beams and are detected astopographical features. Fish in the water also create their owncharacteristic sonar returns.

In a downscan configuration, a transducer may transmit sound waves 12directly down beneath the boat 10 and the transducer or another,receiving transducer, may receive downscan sonar returns from an areagenerally beneath the boat. The number of downscan returns received overtime may produce a plot of the distance traveled by each return, whichmay illustrate the vertical distance to the surface 14 from which thereturns are reflected. In a sidescan configuration, a transducer maytransmit sound waves 12 to one or both sides of the boat (e.g., in afan-shaped beam), and the transducer, or a receiving transducer, mayreceive the sidescan returns. The number of sidescan returns receivedover time may produce a horizontal plot of the distance to each return,which may illustrate the profile of the surface 14 to either side of theboat.

Embodiments of the present invention may include multiple transducerelements in either or both of a downscan configuration and a sidescanconfiguration cooperating to receive returns from the underwaterenvironment. The returns may be compared via the process ofinterferometry to determine the position from which each sonar returnoriginated. In some embodiments, the return data may generate an anglefrom the transducer to each position from which the returns arereceived. The angle value may allow the sonar system to plot theposition of the returns in three dimensional space in order to constructa 3D image of the underwater environment.

The active element in a given transducer may comprise at least onecrystal. Wires are soldered to these coatings so the crystal can beattached to a cable which transfers the electrical energy from thetransmitter to the crystal. As an example, when the frequency of theelectrical signal is the same as the mechanical resonant frequency ofthe crystal, the crystal moves, creating sound waves at that frequency.The shape of the crystal determines both its resonant frequency andshape and angle of the emanated sound beam. Further informationregarding creation of sound energy by differently shaped transducerelements may be found in the article “ITC Application Equations forUnderwater Sound Transducers”, which was published by InternationalTransducer Corporation in 1995, Rev. 8/00, which is hereby incorporatedby reference in its entirety.

Frequencies used by sonar devices vary but the most common ones rangefrom 50 KHz to over 900 KHz depending on application. Some sonar systemsvary the frequency within each sonar pulse using “chirp” technology.These frequencies are in the ultrasonic sound spectrum and are inaudibleto humans.

Example System Architecture

FIG. 2 shows a basic block diagram of a sonar system 30 capable for usewith several embodiments of the present invention. As shown, the sonarsystem 30 may include a number of different modules or components, eachof which may comprise any device or means embodied in either hardware,software, or a combination of hardware and software configured toperform one or more corresponding functions. For example, the sonarsystem 30 may include a sonar signal processor 32, a transceiver 34, anda transducer assembly 36. The sonar system 30 may further include astorage module 37 for storing sonar return data and other dataassociated with the sonar system in a non-transitory computer readablemedium. The sonar system 30 may also include one or more communicationsmodules 38 configured to communicate with one another in any of a numberof different manners including, for example, via a network. In thisregard, the communications module 38 may include any of a number ofdifferent communication backbones or frameworks including, for example,Ethernet, the NMEA 2000 framework, GPS, cellular, WiFi, or othersuitable networks. The network may also support other data sources,including GPS, autopilot, engine data, compass, radar, etc. Numerousother peripheral devices such as one or more wired or wirelessmulti-function displays 40 may be included in the sonar system 30.

With reference to FIG. 4, one or more sonar systems 30 may connect toexternal systems via the communications module 38. In this manner, thesonar system 30 may retrieve stored data from a remote, external server52, 54 via a network 56 in addition to or as an alternative to theonboard storage module 37.

The display 40 may be configured to display images and may include orotherwise be in communication with a user interface 42 configured toreceive an input from a user. The display 40 may be, for example, aconventional LCD (liquid crystal display), a touch screen display,mobile device, or any other suitable display known in the art upon whichimages may be displayed. Although the display 40 of FIG. 2 is shown asbeing connected to the sonar signal processor 32 via the communicationsmodule 38 (e.g., via a network and/or via an Ethernet hub), the display40 could alternatively be in direct communication with the sonar signalprocessor 32 in some embodiments, or the display 40, sonar signalprocessor 32 and user interface 42 could be in a single housing. Theuser interface 42 may include, for example, a keyboard, keypad, functionkeys, mouse, scrolling device, input/output ports, touch screen, or anyother mechanism by which a user may interface with the system. Moreover,in some cases, the user interface 42 may be a portion of one or more ofthe displays 40.

The transducer assembly 36 according to an exemplary embodiment may beprovided in one or more housings (e.g., the housing 58 shown in FIG. 6)that provide for flexible mounting with respect to a hull of the vesselon which the sonar system 30 is employed. In this regard, for example,the housing may be mounted onto the hull of the vessel or onto a deviceor component that may be attached to the hull (e.g., a trolling motor orother steerable device, or another component that is mountable relativeto the hull of the vessel), including a bracket that is adjustable onmultiple axes, permitting omnidirectional movement of the housing.

The transducer assembly 36 may include one or more transducer elementspositioned within the housing, as described in greater detail below. Insome embodiments, each of the transducer elements may be positionedwithin the housing so as to point toward a predetermined area under orto the side of the vessel. For example, some example transducerassemblies (e.g., shown in FIGS. 6, 12-18) are configured such that thetransducer elements are oriented within the housing such that one ormore transducer elements face generally downwardly (e.g., a downscantransducer element 50 shown in FIG. 3A or downscan transducer assembly47 shown in FIG. 3C-3D) and two or more other transducer elements mayadditionally or alternatively face generally outwardly and downwardly(e.g., sidescan transducer arrays of FIGS. 3A, 3B, and 3D).

Referring to FIG. 3A, in some embodiments, the transducer assembly 36may include a first sidescan array 46 and a second sidescan array 48.Each array may have one or more transducer elements, which may includeone or more transmitting elements, one or more receiving elements, andone or more transmit/receive elements, as detailed below. In someembodiments, the transducer assembly 36 may additionally include adownscan transducer 50, which, in some embodiments, may be configured asa transmit/receive element.

In some alternative embodiments, as shown in FIG. 3B, the transducerassembly 36 may not include a downscan transducer. In such embodiments,as detailed herein, the sidescan sonar arrays 46, 48 may each beconfigured to transmit sonar pulses and receive sonar returns.

Turning to FIG. 3C, another embodiment of the present invention mayinclude a transducer array in the downscan configuration. Such adownscan transducer array 47 may transmit sonar pulses with one or moretransducer elements and may receive sonar returns with one or moretransducer elements in a manner similar to the sidescan transducerarrays 46, 48 detailed above. Additionally or alternatively, thedownscan transducer array 47 may be used alone or in combination withone or more sidescan transducer arrays 46, 48 as shown in FIG. 3D. Asdetailed herein, description of various embodiments of a “transducerarray” may apply to each of the sidescan 46, 48 or downscan 47transducer arrays unless otherwise specified.

Example Sidescan Interferometry

As detailed herein, embodiments of the present invention may generate 3Dmesh data by interferometrically processing returns from the same areaof the underwater environment with two or more transducer elements todetermine the angle of each return and plot the returns in 3D space togenerate a 3D image. With reference to FIGS. 5A and 5B, the transducerassembly 36 may emit a fan shaped beam downwardly and outwardly fromeither side of the boat. The fan-shaped beam may have a relativelynarrow beamwidth in a direction parallel to a fore-to-aft direction ofthe vessel and a relatively wide beamwidth in a direction perpendicularto the fore-to-aft direction of the vessel. In some embodiments, asdetailed below, the downscan transducer 50 transmits the fan-shapedbeam, and the sidescan transducer arrays 46, 48 receive returns from thesonar pulses transmitted by the downscan transducer. In some alternativeembodiments, one or more elements of the sidescan transducer arrays 46,48 may transmit sonar pulses. Alternatively, as described in greaterdetail below, a downscan transducer array (e.g., the downscan transducerarray 47 of FIGS. 3C, 3D) may be used, either alone or in combinationwith additional arrays, in a similar manner to the sidescan transducerarrays detailed herein.

Turning to FIG. 6, a cross-sectional view of an example transducerassembly 75 is shown. Each sidescan transducer array 46, 48 is shownhaving two transducer elements 60, 62. In some embodiments, the downscantransducer 50 transmits sonar pulses at least downwardly in a fan-shapedbeam (e.g., shown in FIGS. 5A-5B), and each of the sidescan transducerarrays 46, 48 is configured to receive returns from the underwaterenvironment on its respective side of the housing. The sidescantransducer arrays 46, 48 may be oriented downwardly and outwardly intheir respective directions.

While traditional sidescan may utilize a single sidescan transducerelement on either side of the housing for receiving sidescan sonarreturns, embodiments of the present invention may use at least twosidescan transducer elements 60, 62 positioned in a sidescan transducerarray 46, 48 on the same side of the housing 58. In such embodiments,the sidescan transducer elements 60, 62 may be positioned in parallelmounting slots of an absorptive material 68 within each respectivetransducer array 46, 48. As discussed in greater detail below, thetransducer arrays 46, 48 may include a shielding material 70 forpreventing interference between transducers and improving the returndata.

With continuing reference to FIG. 6, the transducer arrays 46, 48 may beheld at a predetermined angle relative to the surface of the body ofwater. For example, the emitting surfaces of the transducer arrays 46,48 may be oriented at 30 degrees from the surface of the body of waterin order to transmit and/or receive sonar pulses. In some embodiments,an emitting surface of the downscan transducer 50 may be perpendicularto the surface of the body of water. The transducer elements 60, 62 mayalso be positioned at a predetermined distance from each other (e.g., apredetermined distance between the centers of the transducer elements,also referred to as element pitch). The predetermined distance may bedesigned based on the frequency or wavelength of the sonar pulses. Forexample, the predetermined distance between the transducer elements 60,62 may be a fraction or multiple of the wavelength of the sonar pulses(e.g., 1/10, ⅛, ⅙, ¼, ½, 1, 2, 3, or 4 times the wavelength). In someembodiments, the predetermined distance may be less than or equal tohalf the wavelength of the sonar pulses, as discussed below. In otherembodiments, as detailed herein, the predetermined distance may begreater than or equal to half the wavelength of the sonar pulses.

Turning to FIG. 7, a simplified example is shown of the sidescantransducer elements 60, 62 receiving returns from a single point 74 onthe floor of the body of water or other reflecting surface to generate apoint of return data including a distance and/or time to the point aswell as an angle α. During actual interferometric sonar sounding, sonarreturns may be received from across the entire beam width of thetransmitted sonar pulses to generate a plurality of points of returndata in two-dimensional slices from each transmitted sonar pulse. In theembodiment shown in FIG. 7, the downscan sonar transducer 50 maytransmit sonar pulses in a fan-shaped beam towards the floor 14 of thebody of water. The returns A, B may originate at the same time from thesame point 74 and be received by the first 60 and second 62 transducerelements respectively.

Each of the sidescan transducer elements 60, 62 may produceone-dimensional distance data in response to receiving sonar returns A,B, respectively, from the point 74. The sonar signal processor maycombine this one-dimensional distance data from each element with thepredetermined distance between the elements and the angle α between theorientation of the transducer array 46, 48 and the surface of the bodyof water to determine the position of the point 74 of origin of thesonar return. The position of the point 74 may be represented astwo-dimensional coordinates with respect to the boat or housing, or mayalternatively be represented as a distance and angle from the boat orhousing. In yet another embodiment, the position may be determined as anabsolute position value by comparing the interferometric data with GPSor other positioning data. For example, if the first transducer element60 receives returns from the point 74 at a distance of 6.01 feet away(e.g., determined as the speed of the returns over the time fromtransmission to receipt halved) and the second transducer element 62receives returns from the point 74 at 5.99 feet away, the sonar systemmay determine the angle to the point 74. For simplicity of example, ifthe predetermined distance between elements is 0.1 feet, the sonarsignal processor may triangulate the angle α between the firsttransducer element 60 and the first sonar return A as approximately 78degrees and the angle γ between the second transducer element 62 and thesecond sonar return B as approximately 78.9 degrees. As detailed herein,the angle may be determined relative to any reference point based on thedistance (time) data.

In some embodiments, the location of the point of origin for the sonarreturns may be determined via a phase difference between the returnsreceived at the respective transducer elements 60, 62. Turning to FIG.8, another simplified example of a transducer array 46, 48 receivingsonar returns A, B is shown. In this embodiment, the sonar returns fromthe point 74 are represented as waves A, B received by the first 60 andsecond 62 sidescan transducer elements. The returns A, B originatingfrom the same point 74 on the floor of the body of water or otherreflecting surface may have substantially the same frequency, amplitude,and wavelength. Given that the waves A, B may be expected to have thesame properties when received at both the first 60 and second 62sidescan transducer element, a phase difference between the two waves,in combination with the predetermined distance and angle of thetransducer array, may provide the location of their point 74 of origin.As shown in FIG. 8, the returns A, B may be received by the respectivetransducer elements 60, 62 at different positions 76, 78 along therespective waves. The phase, or position, of the wave at the point it isreceived by the transducer elements may be compared to determine theangle of the point 74 of origin.

FIG. 9 shows a plot overlaying the returns A, B as received by eachtransducer element 60, 62 versus time. The phase difference θ betweenthe returns A, B may indicate the degree of offset between the returns,which, when combined with the predetermined distance d, one-dimensionaldistance data, frequency of the returns, and/or angle of the transducerarrays may produce the position of the point 74 of origin. The angle βto the point 74 may be represented by the following Equation (1):

$\begin{matrix}{\beta = {\arcsin\left( \frac{\lambda\;\theta}{2\;\pi\; d} \right)}} & (1)\end{matrix}$

Where λ represents the wavelength of the return, θ represents thereceived phase difference, and d represents the predetermined distance.

In some alternative embodiments, a transducer array may include asidescan element and a downscan transducer element each configured toreceive sonar returns from overlapping regions of the underwaterenvironment. In such embodiments, the sonar returns from the overlappingregions may be used to determine an angle to the point of origin of eachof the sonar returns in a similar manner to the transducer arraysdescribed herein. In some embodiments, the sonar signal processor may beconfigured to compensate for any difference in size or orientation ofthe respective downscan and sidescan elements.

In some embodiments, the transducer arrays may include more than twotransducer elements. For example, FIG. 10 shows an embodiment of thetransducer arrays 80 having three transducer elements 82, 84, 86positioned in mounting slots formed by an absorption material 88. Thearray 80 may further include shielding 90 as detailed herein. Each ofthe transducer elements 82, 84, 86 may be positioned a predetermineddistance d1, d2, d3 from each other. In some embodiments, the distancebetween elements may differ. For example, in the embodiment shown inFIG. 10, the center 84 and left 82 elements are positioned 0.6 mm(˜0.0236 inches) apart, and the center 84 and right 86 elements arepositioned 1.83 mm (˜0.0720 inches) apart. In some embodiments, eachelement may be the same size (e.g., 1.5 mm (˜0.05906 inches) wide). Insome alternative embodiments, one or more of the elements (e.g., element86 of FIG. 10) may differ in size from the remaining elements (e.g., 3.1mm (˜0.12205 inches) in the embodiment of FIG. 10).

In some further embodiments, the predetermined distance between elementsmay be nonredundant, such that each pair of elements is spaced at adifferent predetermined distance. For example, in FIG. 10, eachpredetermined distance d1, d2, d3 may be different, such that d1 is lessthan d2, which are both less than d3. Alternatively, the spacing betweenelements may be interchanged (e.g., such that d1 is greater than d2). Asdetailed below, the nonredundant predetermined distances d1, d2, d3 mayallow each sub-array (e.g., each pairwise array within the transducerarray) to generate a unique solution during the interferometric soundingprocess. In some alternative embodiments, the elements may be evenlyspaced.

In some embodiments, the transducer elements 82, 84, 86 may be used inpairwise sub-arrays to generate more robust return data. For example, inthe embodiment shown in FIG. 10, the first 82 and second 84 elements maybe used to determine the two dimensional return data of the positions ofsonar returns in a manner similar to the two-element embodimentsdescribed herein (e.g., using a phase difference between the respectivereturns). Similarly, the second 84 and third 86 elements may generatethe two dimensional return data of the positions of the floor of thebody of water or other reflecting surface (e.g., fish, objects, etc.).The first 82 and third 86 elements may also generate the two dimensionalreturn data of the positions of the floor of the body of water or otherreflecting surface as detailed herein. Alternatively, any subset of theindividual pairs may be used. As detailed below, each of the pairwisesets of return data may then be correlated (e.g., combined, compared,among others) to generate a more robust set of return data.

These elements 82, 84, 86 may be electrified substantiallysimultaneously to receive the return data, and each of the pairwisecomparisons may then be generated from the received data by the sonarsignal processor. In some alternative embodiments, each of the pairs(e.g., the first 82 and second 84 elements, the first 82 and third 86elements, and the second 84 and third 86 elements) may be sequentiallyelectrified to receive sonar returns separately. In some embodiments,the transmitting transducer(s) may be electrified to transmit a sonarpulse and the receiving transducer(s) may be electrified at apredetermined time thereafter to receive the sonar returns from thetransmitted pulse. In the sequential embodiments detailed herein, asingle sonar pulse may be transmitted for all of the received pairwisereturns (e.g., a pulse that is long enough for each set of pairwiseelements to receive), or, alternatively, multiple pulses may betransmitted.

In yet another embodiment, the transducer arrays may include more thanthree transducer elements. For example, FIGS. 11A-11B shows anembodiment of the transducer arrays 92 having four transducer elements94, 96, 98, 100 positioned in mounting slots formed by an absorptionmaterial 102. The array 92 may further include shielding 104 as detailedherein. Each of the transducer elements 94, 96, 98, 100 may also bepositioned a predetermined distance from each other. In someembodiments, the distance between elements may differ. For example, inthe embodiment shown in FIG. 10, the two left-most elements 94, 96 maybe positioned 0.6 mm (˜0.0236 inches) apart, and the right-most elements98, 100 are positioned 0.6 mm (˜0.0236 inches) apart. The center twoelements 96, 98 may be positioned 1.63 mm (˜0.06417 inches) apart, 1.83mm (˜0.0720 inches) apart, or another predetermined distance apart. Insome alternative embodiments, the elements may be evenly spaced. In someembodiments, each of the transducer elements 94, 96, 98, 100, may beapproximately 1.5 mm (˜0.05906 inches) wide. Alternatively, someelements may differ in size (e.g., as detailed above with respect toFIG. 10).

Turning to FIG. 11A, in some embodiments, the four elements 94, 96, 98,100 may be used in a pairwise fashion as described above. Returns fromeach of the possible pairs, including the first 94 and second 96elements, the first 94 and third 98 elements, the first 94 and fourth100 elements, the second 96 and third 98 elements, the second 96 andfourth 100 elements, and the third 98 and fourth 100 elements, may bespaced at predetermined distances d4, d5, d6, d7, d8, d9 andindividually used in a manner similar to the two and three elementembodiments detailed herein. Any number of additional elements (e.g.,fifth, sixth, seventh, eighth, ninth, or tenth elements) may be utilizedin the transducer array 92 in the same manner as detailed herein.

Turning to FIG. 11B, in some embodiments, two or more transducerelements may be electrically connected in parallel to act as a singleelement. For example, the right-most elements 98, 100 may be connectedin parallel to act as a single element in a similar manner to theright-most element 86 of FIG. 10. In such embodiments, the combinationof elements 98 and 100 may be referred to as a single transducerelement. With continued reference to FIG. 11B, the predetermineddistances d10, d11, d12 may be arranged as if the electrically connectedelements were a single element (e.g., with an effective predetermineddistance d12 to the center of the multiple elements 98, 100). Also, asdetailed above, any of the transducer elements described herein (e.g.,transducer elements 94, 96, 98, 100 shown in FIGS. 11A-11B) may comprisemultiple, electrically connected elements, either directly abutting orspaced, configured to act as a single transducer element.

In some embodiments, the electrically coupled transducer elements (e.g.,elements 98, 100 of the transducer array 92) may be configured totransmit sonar pulses into the water. The spacing between theelectrically coupled elements may be correlated to the width of thetransmitted beam (e.g., a wider spacing may produce a narrower beam),which may allow the transmitted sonar pulses to be precisely designed tomatch the receive angle of the transducer elements. As detailed below,each of the possible array pairs may have a size of receive beam thatdepends upon the predetermined distance between the elements in thepair. In some embodiments, the smaller the predetermined distance (e.g.,the closer the pair of elements are in each sub-array), the wider thereceive beam. For example, the narrowest pair of transducer elements(e.g., elements 94, 96 of the array 92 of FIG. 11B), sometimes referredto as a “coarse” array, may have a wider receive beam than the widestpair of transducer elements (e.g., elements 94 and the combined element98, 100 of the array 92 of FIG. 11B). In such embodiments, thetransmitting transducer (e.g., any of the individual or combinedtransducer elements 94, 96, 98, 100 of the transducer array or aseparate transducer element 50) may be configured to ensonify a regionof the underwater environment that causes sonar returns to be receivedwithin the receive beam of the coarse array transducers. For example, inan embodiment using the dual crystal transmit transducers 98, 100, thedistance between the transducers may be configured to produce a beamfrom the emitting surface of the transmit transducers that has an angleof approximately ±48 degrees.

FIG. 12 depicts an embodiment of a transducer assembly 75 having twotransducer arrays 92 with four transducer elements 94, 96, 98, 100. Asdetailed above, each of the transducer arrays 92 may receive sonarreturns from a respective side of the housing 58 to generate a 3D imageof the underwater environment. In some embodiments, the emitting surfaceof each transducer array 92 may be angled with respect to the surface ofthe body of water. In some embodiments the emitting surface may bedisposed at 30 degrees relative to the surface of the body of water.

With reference to FIG. 13, some embodiments of the transducer arrays 92′may be curved in shape. Such embodiments may be configured to receive awider range of sonar returns than a linear array (e.g., as shown in FIG.12) but may otherwise operate in the same manner. In such embodiments,the angle of the emitting surface of the transducer arrays 92′ maychange along the width of the transducer array.

With reference to FIG. 14, an embodiment of a transducer assembly isshown having circuitry 124 (e.g., a sonar signal processor and/ortransceiver) positioned in the housing 58. As detailed above, thetransducer arrays 92 may be substantially rectangular in shape andextend longitudinally through the housing 58. In some embodiments, ashielding 126 may form a framework to hold the transducer arrays 92 andthe downscan transducer 50 in a predetermined orientation with respectto each other and the housing 58. In this manner, the transducerelements 94, 96, 98, 100 may be positioned relative to one anotherand/or relative to the remaining transducers in the housing 58 bydefining the mounting slots at a predetermined position in theabsorptive material 102 in the shielding framework 126 and inserting thetransducer elements into the mounting slots of the absorptive material.In such embodiments, the absorptive material 102 may define channels inwhich the transducer elements 94, 96, 98, 100 are positioned. Theabsorptive material 102 may enclose the transducer elements 94, 96, 98,100 on three longitudinal sides and/or on opposite ends, such that oneor more emitting surfaces are exposed. As detailed herein, the shieldingand/or absorptive material may be removed from one or more sides toincrease the transmitting and/or receiving beam width of a transducerelement.

FIG. 15 depicts an embodiment of the present invention in which thedownscan transducer 50 transmits sonar pulses for receipt by thesidescan transducer arrays 92 during interferometric imaging. In someembodiments, the downscan transducer may transmit sonar pulsesdownwardly and outwardly in a fan-shaped beam from one or more emittingsurfaces 50 b, 50 c, 50 d (e.g., as shown in FIGS. 5A, 5B). The sonarpulses may echo from one or more surfaces in the water (e.g., the floorof the body of water, fish, or other reflective surfaces) and return toone or both transducer arrays 92. For example, in the embodiment shownin FIG. 15, the downscan transducer transmits sonar pulses, which may bereceived as returns by both arrays 92.

With continuing reference to FIG. 15, in some embodiments, the downscantransducer may include a shielding 106 and or sound absorption material108 positioned on one or more sides 50 a, 50 b, 50 c, 50 d of thedownscan transducer element 50. Each surface 50 a, 50 b, 50 c, 50 d ofthe transducer element 50 may be configured to transmit fan-shaped sonarbeams. In the depicted embodiment, the downscan transducer element 50 isnow configured to transmit sonar pulses in the form of a fan-shaped beamfrom the bottom surface 50 c and the opposing side surfaces 50 b, 50 dwithout transmitting sonar pulses from the top surface 50 a. Thus, thefirst transducer element 50 is configured to emit a fan-shaped beam ofsonar pulses in a direction substantially perpendicular to the surfaceof the water (e.g., beam 110 c), as well as in opposite directions thatare substantially parallel to the surface of the water (e.g., beams 110b, 110 d). This provides a wider coverage of sonar pulses and, mayprovide a similar coverage of sonar pulses as the transducer assembly 75of FIGS. 6, 12, and 13. Along these same lines, the beams 110 b, 110 c,110 d shown in FIG. 15 are conceptual in nature. Therefore, while gapsare shown in between each of the beams 110 b, 110 c, 110 d, in someembodiments, the downscan transducer element 50 may not include gapswhen transmitting sonar pulses and, thus, full coverage below and to thesides of the first transducer element 66 is obtained. For example, thebeams 110 b, 110 c, 110 d may provide substantially continuous sonarcoverage from one side of a vessel to an opposite side of the vessel toprovide sonar returns to each transducer array.

While the downscan transducer element 50 shown in FIG. 15 is a lineartransducer element that produces fan-shaped sonar beams, other shapedtransducer elements can be used (e.g., oval, elliptical, taperedpatterned array, amplitude tapered array, etc.).

In some alternative embodiments, the sidescan transducer arrays maytransmit and receive sonar pulses for interferometry. For example, withreference to FIG. 16, the sidescan transducer arrays 112 may transmitsonar pulses from one or more sidescan transducer elements and receivesonar returns from the transmitted pulses. Each transducer array 112 maytransmit sonar pulses in a fan-shaped beam 122 on its respective side ofthe housing 58 to generate sonar returns from the reflected sonarpulses. The fan-shaped beam may be transmitted by any of the transducerelements 114, 116, 118, 120. In some embodiments, the lowest transducerelement 120 may transmit the fan-shaped beam 122. In some embodiments,two transducer elements (e.g., elements 118 and 120 in FIG. 16) may beelectrically connected in parallel to act as one transducer element, asdescribed herein. In such embodiments, the coupled elements 118, 120 maycombine to transmit the fan-shaped beam. FIG. 16 illustrates asimplified approximation of the two electrically coupled elements 118,120 transmitting sonar pulses 122 from a position approximately betweenthe elements; however in practice the beam 122 may originate as twoseparate beams from both elements that overlap to form a single beam. Asdetailed above, the dual crystal transmit transducer 118, 120 maycontrol the width of the transmitted beam by adjusting the distancebetween the elements. Similarly, embodiments of the transducer arrayswith one, two, three, or greater than four transducer elements may alsotransmit sonar pulses.

With continued reference to FIG. 16, after the sonar pulses aretransmitted by the transducer element(s), one or more of the sidescantransducer elements 114, 116, 118, 120 may receive the correspondingsonar returns. In some embodiments, each of the elements may receive thesonar returns and perform interferometry as detailed herein, forexample, with respect to FIGS. 6 and 10-13. In other embodiments, asubset of the transducer elements 114, 116, 118, 120 may receive thesonar returns. For example, the elements not transmitting sonar pulsesmay receive the returns, such that each transducer element is either atransmit-only or receive-only element. In other embodiments thetransmitting transducer(s) may also be configured to receive thecorresponding sonar returns. In some embodiments, the transducer arrays112 may operate in a similar manner as described in other embodiments ofthe transducer arrays herein.

Downscan Interferometry

In some embodiments, the downscan transducer element 50 (shown in FIG.15) may be replaced with a downscan transducer array 47 as shown in FIG.17. The downscan transducer array 47 may include the same structure andfunction as described herein with respect to the sidescan transducerarrays (e.g., sidescan transducer array 92 shown in FIG. 15) with theexception of the orientation of the array.

Embodiments of the downscan transducer array 47 may include two or moredownscan transducer elements 294, 296, 298, 300 configured to transmitdownscan sonar pulses and/or receive downscan sonar returns. Similar tothe sidescan transducer array 92, the downscan transducer array 47 maytransmit sonar pulses with one or more downscan transducer elements 294,296, 298, 300 and receive sonar returns with two or more downscantransducer elements 294, 296, 298, 300 to interferometrically determinethe position of the point of origin of the sonar returns.

In some embodiments, at least one of the two center downscan transducerelements 296, 298 may be configured to transmit the downscan sonarpulses. Alternatively, at least one of the other downscan transducerelements 294, 300 may be configured to transmit the downscan sonarpulses. In some embodiments, as detailed above with respect to thesidescan transducer arrays, two or more of the downscan transducerelements 294, 296, 298, 300 may be electrically coupled in parallel toact as a single element. For example, the left two 294, 296, the centertwo 296, 298, or the right two 298, 300 downscan transducer elements maybe electrically coupled in parallel to transmit and/or receive as asingle element.

Also, as detailed above with respect to the sidescan transducer arrays,the downscan transducer elements may receive downscan sonar returns withmore than one element to interferometrically determine the angle to thepoint of origin of the sonar returns. In some embodiments, the receivingdownscan transducer elements may operate in a pairwise fashion toproduce more robust return data. Each of the respective pairs (e.g., thefirst 294 and second 296 transducer elements, the first 294 and third298 transducer elements, the first 294 and fourth 300 transducerelements, the second 296 and third 298 transducer elements, the second296 and fourth 300 transducer elements, and the third 298 and fourth 300transducer elements) may be used to generate a set of downscan returndata. In some further embodiments, a subset of the downscan transducerelements 294, 296, 298, 300 may be used to generate the downscan returndata. For example, in some embodiments, each of the transducer elements294, 296, 298, 300 may be configured to either transmit only or receiveonly.

In some embodiments the downscan transducer array 47 may be used alonein the housing 58 with no sidescan transducer arrays 92 as shown in FIG.18. In such embodiments, the 3D mesh data may be formed from theinterferometric data generated by the downscan transducer array. In somealternative embodiments, both a downscan transducer array 47 and one ormore sidescan transducer arrays 92 may be used to generate 3D mesh data.In such embodiments, each array may independently transmit sonar pulsesand receive sonar returns as described herein, or, alternatively, one ormore of the transducer arrays (e.g., the downscan transducer array 47)may transmit sonar pulses and receive sonar returns and the remainingtransducer arrays may receive only. In some further embodiments, thedownscan transducer 47 array may transmit only. The downscan transducerarray 47 may be straight in a widthwise direction such that all of theemitting surfaces of the transducer elements 294, 296, 298, 300 aresubstantially coplanar (e.g., as detailed above with respect to thesidescan transducer array 92 of FIG. 12) or alternatively, the downscantransducer array 47 may be curved (e.g., as shown with respect to thesidescan transducer array 92′ of FIG. 13).

In some embodiments, the downscan transducer array 47 may be replaced byangling the sidescan transducer arrays 92 lower from the horizon. Forexample, the sidescan transducer arrays may be positioned at 45 degreesrelative to the surface of the body of water. In yet some furtherembodiments, the downscan transducer array 47 may be joined with thesidescan transducer arrays 92 within a single shielding to define acontinuous array of transducer elements about the perimeter of thehousing 58. In such embodiments, the combined transducer array may becurved (e.g., in the same manner as detailed herein with respect to asingle transducer array) or may have angled sections in substantiallythe same positions as the sidescan transducer arrays 92.

In some embodiments, the downscan transducer array 47 may include ashielding 302 and/or absorption material 304 defining mounting slots forpositioning and isolating the elements 294, 296, 298, 300. In somealternative embodiments, the shielding 302 and/or absorption material304 may be removed from the side surfaces of the downscan transducerarray 47 as shown with respect to the downscan transducer element 50 ofFIG. 15.

In some embodiments, with reference to FIG. 19, the transducer assemblyincluding one or more of a downscan transducer array and sidescantransducer array, may be angled forward such that the beam istransmitted at least partially forward relative to the direction oftravel of the boat. For example, FIG. 19 shows a transducer assembly 305angled forward from a direction perpendicular to the surface of the bodyof water, such that the beam may be angled at least partially forwardrelative to the boat. The transducer assembly 305 may comprise any ofthe transducer assembly embodiments detailed herein and may include ahousing 310 and at least one transducer array 315. In the embodiment ofFIG. 19, the transducer array may include two or more linear transducerelements that transmit a fan-shaped beam. The fan-shaped beam may have along edge perpendicular to the direction of travel of the boat (e.g.,such that a length of the transducer elements is oriented along the keelof the vessel similar to FIGS. 5A and 5B). In some other embodiments,the transducer elements of the one or more transducer arrays may beoriented perpendicular to the direction of travel, such that thefan-shaped beam is produced along a plane defined vertically from thecenterline of the boat. In some further embodiments, other beam shapes(e.g., conical shaped, elliptical shaped, multiple conical shaped, etc.)may be used. Additional examples of transducer array orientations,configurations, processing, and other information may be found in U.S.patent application Ser. No. 14/618,987 filed Feb. 10, 2015, and entitled“A Transducer Array having a Transceiver,” which reference is herebyincorporated by reference herein in its entirety.

Example Interferometric Processing and 3D Imaging

The following describes various example embodiments for transforming andrendering raw sonar data in different contexts, which may be performedby the sonar systems 30, through the configuration of the sonar module44. It is understood that the sonar systems 30 described herein aremerely examples of computing systems that may be configured to performthe various functionalities. For example, computing systems that are notconfigured for mounting to a watercraft and do not have interfaces tosonar transducer elements may be configured to perform at least some ofthe functionality described herein. Additionally, it will be apparent toone of skill in the art that the following described functionalities maybe performed together in a unified manner or as separate, independentfunctions where appropriate.

As detailed herein, embodiments of the transducer assembly may beconfigured to receive sonar returns from substantially the same area ofthe underwater environment using two or more transducer elements. Thetwo or more transducer elements may determine a position of the receivedreturns by comparing the respective returns received at each element.While some embodiments illustrate outputs with respect to one type oftransducer array (e.g., sidescan transducer arrays), any type of array(e.g., downscan transducer arrays or sidescan transducer arrays) mayproduce similar results unless otherwise indicated.

Each of the pair-wise array combinations may be defined by thepredetermined distance between the respective transducer elements. Theacoustic receive sensitivity of each sub-array may vary depending on thepredetermined distances between the elements of each array combination.As detailed above, the phase shift with respect to incident angle isrelated to the predetermined distance between the elements as rewrittenin Equation (2):

$\begin{matrix}{{\frac{2\;\pi}{\lambda}d\;{\sin(\beta)}} = \theta} & (2)\end{matrix}$

Accordingly, the phase shift may vary with incident angle more rapidlyfor larger d. In some embodiments, a transducer array having multipletransducer elements may mange the elements according to the nonredundantspacing techniques described herein in order to stagger the precisionand noise of each sub-array to produce a more robust transducer array.In particular, a “coarse” array may have the smallest predetermineddistance d (e.g., the predetermined distance d10 between the leftmostelements 94, 96 of FIG. 11B) and thus may be the least sensitive tochanges in incident angle. A “medium” array may have a predetermineddistance d (e.g., the predetermined distance d11 between the combinedright element 98, 100 and the center element 96 of FIG. 11B) that isslightly larger and thus more sensitive to changes in angle. Finally, a“fine” array may have the largest predetermined distance d (e.g., thepredetermined distance d12 between the outer two elements 94 and 98,100) and is thus most sensitive to changes in incident angle.

In the “coarse” array, the pair of elements may receive the leastambiguous data but may also generate the least precise data of thepairwise sub-arrays (e.g., least sensitive to changes in angle). In the“fine” array, the pair of elements may receive somewhat more ambiguousdata, but may also generate the most precise data (e.g., most sensitiveto changes in angle). In some embodiments, the coarse array producesless ambiguous data because phase wrapping may not occur within adesired range of angles that are ensonified, while the fine array may bemore ambiguous because the phase may wrap within the ensonified area. Insuch embodiments, the coarse array may at least partially resolve thedata from the fine array within a specific region, and a single solutionmay thereby be determined for the fine array.

In some alternative embodiments, each of four transducer elements (e.g.,the four sidescan transducer elements 94, 96, 98, 100 shown in FIG. 11Aor the four downscan transducer elements 294, 296, 298, 300 shown inFIG. 17) detailed above may be used in a pairwise fashion to generate upto six sets of return data. Similarly, non-redundant or redundantspacing may be used for any combination of two or more elementsdisclosed herein. For example, in some embodiments, three individualtransducer elements may be used in the same manner as detailed above.Some embodiments may use two transducer elements in a transducer arrayas to generate a single set of interferometric return data. Moreover,some embodiments may automatically or manually allow a user to select asubset of available transducers to receive return data.

In embodiments that generate more than one set of interferometric returndata (e.g., the “coarse,” “medium,” and “fine” arrays of FIG. 11B), thesets of return data may be correlated in a variety of ways to generate afinal set of interferometric return data. In some embodiments, the setsof interferometric return data may be correlated by comparing the setsof data. For example, if three sets of data are used, the sonar signalprocessor may remove points of return data from one of the sets thatsubstantially differ from the other two (e.g., to eliminate noise). Whencomparing two or more sets of data, two points that differ substantiallybetween sets may both be removed. In some embodiments, multiple sets ofinterferometric return data may be correlated (e.g., compared, combined,among others) to generate a more robust set of return data with moredata points.

In some embodiments, the results of each set of data may be averaged toproduce a final result. For example, the angle determined to a givenpoint by a first set of interferometric return data (e.g., a coarsearray) may be averaged with the angle to the same point determined by asecond set of interferometric return data (e.g., a fine array) togenerate a final angle value. Similarly the distance, time, strength,phase, or component coordinate values may be averaged. In suchembodiments, averaging the returns from each of the pairwise arrays mayeliminate noise while also generating more precise return data. In someembodiments, weighting can be used for correlating the sets of data toproduct the final result (e.g., the fine array may be weighteddifferently than the coarse array).

As discussed herein, the transmitting transducer (e.g., the downscantransducer or one or more of the sidescan transducer elements) maytransmit a sonar pulses downwardly and outwardly from the boat, and aplurality of sidescan transducers may receive the corresponding sonarreturns in a pairwise fashion to generate interferometric sonar returndata. In some embodiments, the interferometric return data may bereceived from two-dimensional slices of the underwater environment(e.g., the fan-shaped beams have narrow width in the direction of travelof the watercraft—thereby forming thin slices of a raw sonar data of theunderwater environment). In this regard, each sonar return of the rawsonar data may be defined by, at least, a distance and an angle (e.g.,2D), which may be processed (e.g., by the sonar signal processor 32 ofFIG. 2) to generate 2D sonar data. Further, even though there may besome space within the narrow width of the fan-shaped beam, the 2D sonarreturns can be defined to ignore that width and, thus, be assumed to be2D. The 2D sonar data may be substantially two dimensional sets of dataoriented perpendicular to the direction of travel of the boat (e.g.,parallel to the plane of the fan-shaped beam). With reference to FIG.20, the 2D sonar data may be formed as 2D point clouds with a pluralityof points representing the returns from a reflecting surface of the bodyof water (e.g., fish, sea floor, etc.). FIG. 20 illustrates a simplifiedillustration of a 2D sonar data derived from raw sonar data inaccordance with an embodiment of the present invention. The 2D sonardata may represent a plurality of points representing individual, orgroups of, points 310 from the 2D slice of the underwater environmentfrom which sonar return data is received. For example, the points 310may represent returns from the floor of the body of water 14 or fromother objects from which the sonar pulses echo. For example, FIG. 20depicts a fish 314 in the water column and an object 312 resting on thefloor 14 of the body of water. In some embodiments, the sonar returndata from the 2D slice are saved in memory for processing to form the 3Dmesh data, which may be displayed as a 3D image. In some embodiments 3Dimage data representing a 3D image may be stored in a buffer prior to orin conjunction with display on the screen.

The 2D sonar data may comprise data from two or more transducer arrays(e.g., the sidescan and/or downscan transducer arrays). For example, insome embodiments, a left or first sidescan transducer array may captureinterferometric sonar returns from a portion of a 2D slice on a leftside of the boat and a right or second sidescan transducer array maycapture interferometric sonar returns from a portion of a 2D slice anopposite or right side of the boat. In such embodiments, the 2D sonardata may be defined by joining the raw returns from the first and secondsidescan transducer arrays to form a single data set. In someembodiments the returns from the first and second sidescan transducerarrays may be joined at an axis representing the line of travel of theboat. In some embodiments, raw return data from the downscan transducerarray may be used alone or in combination with one or more sidescantransducer arrays to produce 2D sonar data.

In some embodiments, each set of sonar returns (corresponding to a setof sonar pulses) as the watercraft travels may generate a single sliceof 2D sonar data. The plurality of sets of 2D sonar data (built up asthe watercraft travels) may be processed together and used to generate3D mesh data.

In some embodiments, the 3D mesh data may be produced by combining thepoints of interferometric return data from each set of 2D sonar dataonto a 3D grid to create a 3D point cloud of individual data points. The3D point cloud may then be processed (e.g., using the sonar signalprocessor 32) to generate a mesh based on the overall topography of thepoint cloud.

In some embodiments, 2D sonar data may be processed with one or moreadjacent sets of 2D sonar data to produce an adjusted set of sonar data.The adjusted set of sonar data may include interpolated connectionsbetween the points of 2D sonar data and/or between adjacent sets of 2Dsonar data to visualize the 2D slices of the underwater environment. Theadjusted set of sonar data may represent continuous contours ortopographical meshes such that the 3D mesh data may be formed byconnecting the adjusted sets of sonar data with connecting gridlines320, as shown in FIG. 21.

2D sonar data or adjusted 2D sonar data may be grouped and processedinto sub-combinations or subsets of data before generating final 3D meshdata. In some embodiments, the 3D mesh data may be stored or displayedin multiple, smaller segments that connect with one another, rather thanusing a single, large set of 3D mesh data. For example, after apredetermined number of sets of 2D sonar data or after a predeterminedmemory limit, the 3D mesh data may separate and begin a new segment of3D mesh data. Additionally or alternatively, separate 3D mesh data maybe stored for each array, such that two parallel meshes (e.g., one oneither side of the vessel) are plotted together in the 3D image. In somefurther embodiments, additional or fewer processing steps may berequired to convert the raw sonar data into 3D mesh data, and thepresent disclosure envisions any means of converting raw sonar returndata into 3D mesh data. U.S. Patent Application Ser. No. 62/128,641,filed Mar. 5, 2015, entitled “Reconstruction of Underwater Features for3D Imaging” provides additional detail regarding example systems andmethods of reconstructing a 3D Image and is hereby incorporated byreference herein in its entirety.

In some embodiments, each of the sets of 2D sonar data may be displayedon a display, such as the display 40, by adding the newest 2D slice ontothe front of the previous set of sonar data. The interferometric data ineach set of 2D sonar data may be processed into the 3D mesh data anddisplayed as the 3D image. With reference to FIG. 21, the 3D mesh datamay represent a topographical grid showing the contour of the floor ofthe body of water.

The 3D image may be represented as a waterfall view, wherein each set ofadjusted sonar data (e.g., corresponding to a 2D slice of the underwaterenvironment) is displayed in order, ultimately building up as the boattravels to form the 3D image. In some embodiments, the 3D image may bedisplayed in a perspective view (e.g., as shown in FIGS. 1, 21, and 22)such that the contour of the floor of the body of water is visualized inthree dimensions.

As shown in FIG. 21, the 3D image may also be turned with the movementof the boat such that the gridlines appear to turn as shown in FIG. 21.Alternatively, the mesh may be formed in an absolute grid centeredaround a global coordinate system (e.g., north, south, east, west) andthe mesh may fill in perpendicularly each time. In some embodiments, the3D image may be displayed as a waterfall of 2D sonar data or adjustedsets of sonar data, regardless of the movement of the boat. In otherembodiments, the 2D sonar data or adjusted sets of sonar data may beturned and oriented relative to the direction and movement of the boat.In yet some further embodiments, the 2D sonar data or adjusted sets ofsonar data may be oriented and scaled according to their actual positionin the body of water.

With continued reference to FIG. 22, a simplified view of the 3D imageis shown having the gridlines 320 arranged in a perspective view to showthe three dimensional path of the boat along the bottom of the body ofwater. The path of the boat may be defined by a centerline 322 of thegrid. As such, in embodiments where a sidescan transducer array is used(e.g., the sidescan transducer array 92 of FIG. 12), area to the left324 of the centerline 322 may be produced by a port sidescan transducerarray, and the area to the right 326 of the centerline 322 may beproduced by a starboard sidescan transducer array. In embodiments wherea downscan transducer array is used (e.g., the downscan transducer array47 of FIG. 17) the entire 3D mesh data, or a middle portion thereof,spanning the centerline 322, may be defined by the downscan transducerarray. As detailed above, the returns from the various arrays may notnecessarily about each other directly on the centerline 322, as such,the results may be combined or partitioned to define the 3D mesh data.

The 3D mesh data may further show terrain features on the bottom of thebody of water. For example, a hump 328 is shown in the 3D image of the3D mesh data representing a raised plateau on the bottom of the body ofwater. In some embodiments, the gridlines 320 may represent squares ofconnected data points. In some alternative embodiments, the surface maybe reconstructed as triangles in order to resolve the surface contour.

In some embodiments and as shown in FIGS. 21-22, the adjusted sets ofsonar data may be rendered and plotted by the sonar system inconjunction with positioning information (e.g., GPS, inertial sensors,dead reckoning positioning, etc.). The positioning information maydefine a relative movement between slices, which is then used to adjustthe position of the sonar data on the display 40 relative to theprevious set of sonar data. For example, the 3D image of FIG. 21 turnsas the boat changes its direction of travel. In some furtherembodiments, the positioning information may define an actual geographicposition, such that the location and orientation of the sonar datarepresent an absolute position from which the slice was sounded. In suchembodiments, the device may be scaled and oriented onto a chart, torepresent a 3D image of the reflected surfaces in the body of water atthe same position on the chart.

In some embodiments, the 3D data may also include objects in the watercolumn, such as the fish 330 shown in FIG. 22. In some alternativeembodiments, separate 3D data may be generated for objects in the watercolumn (e.g., the vessel, fish, obstacles, etc.)

With reference to FIG. 29, a flow diagram illustrating an embodiment ofthe interferometric process is shown. In some embodiments, the sonarsystem may transmit sonar pulses with a transmit transducer 4400 (e.g.,a downscan transducer element 50, 294, 296, 298, 300 or a sidescantransducer element 94, 96, 98, 100). One of the transducer elements in atransducer array may receive first sonar returns from the transmittedsonar pulses 4405, and a second transducer element in the array mayreceive second sonar returns 4410. The first and second sonar returndata may be processed to generate a 3D Mesh Data 4415 as detailedherein. In some embodiments, a display (e.g., the display 40 shown inFIG. 2) may display the 3D image 4420.

In some further embodiments, with reference to FIG. 30, a thirdtransducer element may be used. For example, a transmit transducer(e.g., a downscan transducer element 50, 294, 296, 298, 300 or asidescan transducer element 94, 96, 98, 100) may transmit a sonar pulseinto a body of water 4500. First, second, and third transducer elementsmay receive first, second, and third sonar return data respectively4505, 4510, 4515. The sonar system may process the first and secondsonar returns to generate a first set of 2D sonar return data 4520.Similarly, the sonar system may process the first and third sonar returndata to generate a second set of 2D sonar return data 4525. The sonarsystem may then generate a third set of 2D sonar return data based on acomparison of the first and second sets of 2D sonar return data 4530.The sonar system may then generate a 3D mesh data based on the third setof 2D sonar data 4535. In some embodiments, a display (e.g., the display40 shown in FIG. 2) may then display a 3D image based on the 3D meshdata.

In some embodiments, the 3D mesh data detailed above may be furtherprocessed (e.g., by the sonar signal processor 32) to generate a morecomplex 3D image. The 3D mesh data may be processed to represent asmoother image that may give the user an intuitive understanding of thefeatures of the bottom of the body of water. In some embodiments, thesonar system may apply textures or surfaces to the 3D mesh data toindicate the contour, density, depth, or any other characteristic of theimaged surfaces. For example FIG. 22 depicts a smoothed 3D image todepict smoother, more natural contours.

Example Application of Sidescan Imaging

In some embodiments, the embodiments of the sidescan transducer arrays(e.g., sidescan transducer arrays 46, 48, 80, and 92), may additionallyor alternatively be used for sidescan imaging. Sidescan imaging may begenerated by transmitting sidescan sonar pulses with at least oneelement of a sidescan transducer array and receiving sidescan sonarreturns with at least one element of a sidescan transducer array. Withreference to the embodiment of FIG. 6, at least one of the sidescantransducer elements of each array may be configured to transmit sonarpulses which echo from objects in the underwater environment (e.g., thefloor of the body of water, fish, objects, etc.) in a manner similar tothe above-described embodiments. In some embodiments, the transmittedsonar pulses from a sidescan sonar element will define a fan-shaped beamon one side of the boat (e.g., as shown in FIGS. 5A and 5B). At leastone sidescan transducer element may then receive the sonar returns togenerate sidescan sonar image data. Additional examples of sidescansonar imaging systems and methods are shown and described in U.S. PatentPublication No. 2013/0148471, filed Dec. 7, 2011, and entitled “SonarRendering Systems and Associated Methods,” and U.S. Patent PublicationNo. 2013/0208568, filed Feb. 10, 2012, and entitled “Sonar Assembly forReduced Interference,” both of which are hereby incorporated byreference in their entireties.

For example, in the embodiment shown in FIG. 6, the lowermost sidescantransducer element 62 may be configured to transmit sonar pulses and theuppermost sidescan transducer element may be configured to receive sonarpulses. The returns may then be plotted to show the time/distance of thesonar returns from the watercraft to the left and right as thewatercraft travels (e.g. upwardly). An example sidescan image is shownin FIG. 23. In some other embodiments, the uppermost sidescan transducerelement 60 may be configured to transmit-only for sidescan imaging andthe lowermost sidescan transducer element 62 may be configured toreceive-only. In some embodiments, either or both of the lowermosttransducer element 62 and the uppermost transducer element 60 may beconfigured to transmit and receive sonar pulses. As detailed above, anyone or more of the sidescan transducer elements may operate in atransmit-only, receive-only, transmit/receive, or inactive capacity forsidescan imaging.

Also similar to the displayed 3D image detailed above, each sonar columnmay be associated with a scan or beam emission performed by thetransducer or a transducer array at a particular time. Based on a scanrate that may be controlled by processing circuitry of a sonar system,new sonar columns may be generated and prepared for display. Each sonarcolumn may also be associated, by the processing circuitry, to ageo-location at the sonar column's center point. The geo-location of thesonar column may be determined based on the location of the watercraftat the time when the sonar column data was captured as indicated by theposition sensing circuitry. The sonar column may also be time-stamped orgiven a sequence number that may be used to determine the ordering ofthe sonar columns.

In some embodiments, the sonar system of the present invention may beconfigured to simultaneously carry out 3D mesh data generation (viainterferometry) and sidescan sonar imaging. In these embodiments, thesidescan sonar images may either be taken simultaneous with or in rapidsuccession with the interferometric 2D sonar data. For example, thetransmit transducer of the interferometric system (e.g., either one ofthe sidescan transducer elements or a downscan transducer) may transmitat the same time as a sidescan transducer element for sidescan imaging.In some other embodiments, the sidescan transducer array may transmitsidescan sonar pulses in alternating fashion, or in a series ofalternating bursts (e.g., 3 pulses of sidescan transmissions and 3pulses of interferometric pulses). In each of these embodiments, thereceiving elements for either the sidescan imaging or interferometricimaging may be electrified in the same sequence in order to receivetheir respective returns.

In some embodiments, one sidescan transducer element may be configuredto transmit interferometric sonar pulses, while a second sidescantransducer element in the same array may be configured to transmitsidescan sonar pulses. In some embodiments, the same element maytransmit for both sidescan and interferometric imaging. In theseembodiments, one or more elements may transmit a fan-shaped beam, whichmay be received by a plurality of sidescan transducer elements forsimultaneously generating 3D mesh data and sidescan image data.

In some embodiments, the interferometric and sidescan imaging processesmay use different frequencies to allow the transducer elements and sonarsignal processor to distinguish between the respective returns. Forexample, the downscan transducer (or interferometrically transmittingsidescan transducer element) may transmit the interferometric sonarpulses at 600 kHz, and the sidescan transducer element may transmit thesidescan imaging sonar pulses at 480 kHz. One or more of the sidescantransducer elements may be configured to receive both frequencies ofsonar pulses, depending on the electrification of the element at a giventime. In such an embodiment, the interferometric imaging and sidescanimaging may be performed as described above with the sonar signalprocessor and transducer elements automatically sorting betweeninterferometric returns and sidescan returns.

In some embodiments, the sonar system may generate a sidescan sonarimage in addition to the 3D mesh data as detailed above. In suchembodiments, the sonar system (e.g., via the sonar signal processor 32)may combine the sidescan sonar image with the 3D mesh data to generatethe 3D image. The 3D mesh data may represent a 3D visualization of thefloor (or other detected features) of the bottom of the body of water,as detailed above. In some embodiments, combining the sidescan sonarimage data with the 3D mesh data may comprise overlaying the sidescansonar image data onto the topographical features of the 3D mesh data tocreate the appearance of a picture of the bottom of the body of water asshown in FIG. 26. FIG. 26 depicts a simplified version of the overlaidsidescan image taken in large sections with the water column stillincluded for illustration purposes. The 2D segments of the sidescanimage may be significantly narrower such that the sidescan imagesmoothly lies atop a shifting 3D mesh data.

To overlay the sidescan sonar image data onto the 3D mesh data, thewater column (e.g., 405 in FIGS. 23-24) may be removed and the remainingsidescan image may be combined to generate a continuous image of thebottom of the body of water. The sidescan image may then be draped ontothe 3D mesh data to translate the topographical contours of the 3D meshdata onto their corresponding location in the sidescan image as shown inFIG. 26. In some embodiments, the 3D mesh data and/or the sidescan imagedata may be scaled relative to one another such that the respectivepositions align. In some embodiments, the sidescan sonar image may bestretched so that the outer extents of the sidescan sonar image alignwith the extent of the 3D mesh data in the 3D image. In someembodiments, the sonar signal processor (e.g., the sonar signalprocessor 32) may match one or more features on the sidescan image datawith corresponding topographical features on the 3D mesh data and scalethe remainder of the sidescan image accordingly. For example, brighterpixels in the sidescan image (e.g., as shown in FIG. 23) may representprotruding features from the floor of the body of water. These featuresmay be aligned with high points near the same location on the 3D meshdata to scale the sidescan image to size.

The sidescan sonar returns may be simultaneously or sequentiallygenerated with the interferometric data, as detailed above. In suchembodiments, the sonar system may combine the two images automaticallyas they are generated. In some alternative embodiments, the sonar systemmay correlate a time or position data associated with the sidescan and3D mesh data to combine them. The images may be combined even when takenat different times. For example, in some embodiments, a 3D mesh data maybe generated by passing over an area of the body of water in the boat.In a second pass, a sidescan image may be generated. The sidescan imagemay be oriented, scaled, and combined with the 3D mesh data in the 3Dimage based on their respective positions and features regardless of thetime at which they were taken.

With reference to FIG. 31, the interferometric portion of the sonarsystem may transmit sonar pulses into a body of water using a transmittransducer 4600 as detailed in the various embodiments herein. Thetransmitted sonar pulses may be received by a first transducer element4605 (e.g., the sidescan transducer elements 94, 96, 98, 100 or downscantransducer elements 294, 296, 298, 300). The transmitted sonar pulsesmay also be received by a second transducer element 4610 (e.g., thesidescan transducer elements 94, 96, 98, 100 or downscan transducerelements 294, 296, 298, 300). Simultaneously or sequentially withobtaining the interferometric data, the first or second sidescantransducer element may transmit sidescan sonar pulses 4615, as detailedherein. At least one of the first or second sidescan transducer elementsmay receive sidescan sonar returns 4620. The sonar system may generate3D mesh data based on the interferometric data and spacing between thetransducer elements 4625. The sonar system may further generate 3D imagedata, representing the 3D image, based on the 3D mesh data and sidescansonar return data 4630. In some embodiments, a display (e.g., thedisplay 40 shown in FIG. 2) may display the 3D image 4635.

Downscan Imaging

Some embodiments of the transducer arrays (e.g., transducer arrays 46,47, 48, 80, and 92), may additionally or alternatively be used fordownscan imaging. Downscan imaging may be generated by transmitting andreceiving downscan sonar pulses with the downscan transducer element.With reference to the embodiment of FIG. 6, the downscan transducerelement 50 may be configured to transmit sonar pulses which echo fromthe reflecting surfaces in the body of water (e.g., the floor of thebody of water, fish, obstacles, etc.) in a manner similar to theabove-described embodiments. In some embodiments, the downscantransducer element 50 may be a linear downscan transducer, such that thedownscan transducer element is configured to transmit a fan-shaped beam.Alternatively, a downscan transducer array 47 (shown in FIG. 17) may beused to transmit downscan sonar pulses and receive downscan sonarreturns with one or more downscan transducer elements 294, 296, 298,300. In the downscan transducer array 47 embodiments, any one or more ofthe downscan transducer elements 294, 296, 298, 300 may transmit sonarpulses and any one of the elements may receive the respective returns,including using a single element for both or using one element as atransmit-only element and another as a receive-only element. In someother embodiments, a circular downscan transducer may be provided togenerate downscan sonar returns. Downscan imaging may be performed inaccordance with the apparatus and methods disclosed in U.S. Pat. No.8,305,840 and U.S. Pat. No. 8,300,499, which references are incorporatedherein in their entireties.

Downscan sonar returns may be displayed (e.g., on the display 40) toform a two dimensional plot of return distance of sonar returns as thewatercraft travels (e.g., to the right in FIG. 25). FIG. 25 shows on theright side (e.g., right display portion 130), an exemplary screen shotof a circular downscan transducer image that corresponds to the display(e.g., the left side of the figure (left display portion 132)) producedby a linear downscan element of an embodiment (e.g., downscan element50). In this regard, the left display of FIG. 25 shows a boulder on theleft, two tree trunks rising up from the bottom near the center of thedisplay, and, possibly, several fish (white spots) near the lower right.The corresponding same features can be determined from the right display130 (i.e., the circular downscan display). In such an exampleembodiment, the transducer assembly includes two separate downscantransducers (one linear downscan transducer element and one circulardownscan transducer element).

The downscan transducer element 50 or downscan transducer array 47 maybe used to generate downscan returns simultaneously, sequentially, orindependently of the interferometric returns detailed above. In someembodiments, the downscan transducer 50 or downscan transducer array 47may transmit a fan-shaped beam for generating the interferometricreturns with the sidescan transducer arrays (e.g., 46, 48, 80, 92) andmay simultaneously receive the same returns to generate downscan returndata. Alternatively, the downscan transducer element 50 or downscantransducer array 47 may sequentially transmit pulses for interferometricand downscan imaging. In some embodiments, the downscan transducer mayproduce two different frequencies (e.g., 600 and 480) to distinguishbetween downscan and interferometric pulses. In embodiments in which thesidescan transducer array (e.g., 46, 48, 80, 92) transmits sonar pulses,the sidescan and downscan transducers may alternately or simultaneouslytransmit pulses, with or without differing frequencies as discussedabove. In embodiments of the downscan imaging array 47, one element 294,296, 298, 300 may transmit sonar pulses for downscan imaging whileanother element transmits sonar pulses for interferometric imaging.Alternatively, a single element may transmit for both downscan andinterferometric imaging.

In some further embodiments, sidescan imaging may be used, as detailedabove, in combination with or independent from downscan imaging andinterferometric imaging. Moreover, the downscan functionality may beused independently to generate a downscan image.

In some embodiments, the downscan return data (e.g., one-dimensionaldownscan returns) may additionally or alternatively be combined with the3D mesh data. For example, in some embodiments, one dimensional downscansonar returns may be used to apply depth markers to the 3D image alongthe direction of travel. In some further embodiments, the downscan datamay be used to confirm positioning of sonar returns in the 3D mesh data,such as confirming a depth of the sea floor or confirming a depth offish. In some embodiments in which the downscan transducer arrayproduces the 3D mesh data, additional downscan return data (e.g.,one-dimensional downscan returns) may be simultaneously acquired andcombined with the 3D mesh data.

The downscan sonar returns may be simultaneously or sequentiallygenerated with the interferometric data (e.g., receiving downscanreturns from the same sonar pulses that generate the interferometricdata, or alternatively, sequentially transmitting downscan andinterferometric sonar pulses). In such embodiments, the sonar system maycombine the two images automatically as they are generated. In somealternative embodiments, the sonar system may correlate a time orposition data associated with the downscan and 3D mesh data to combinethem. The images may be combined even when taken at different times. Thedownscan image data may be oriented, scaled, and combined with the 3Dmesh data based on their respective positions and features regardless ofthe time at which they were taken.

Data Updating

In some embodiments, preexisting sonar data may be updated or modifiedwith newer sonar data. The sonar data described herein may include 3Dmesh data, sidescan image data, downscan image data, and/or 3D imagedata. With reference to FIG. 32, the sonar system may generate Live 3DMesh Data 4700 via the systems and process detailed herein. The systemmay then determine a position associated with the Live 3D Mesh Data4705, for example, by obtaining GPS or other position data associatedwith the Live sonar data. The system may then update at least a portionof a Stored 3D Mesh Data 4710 using the Live 3D Mesh Data and based onthe position associated with the Live data.

In some embodiments, Stored 3D Mesh Data that was generated previously,either by the sonar system or by another sonar system and stored, may beupdated with Live data as the boat travels over the body of water.Similarly, Stored data may be generated from live data in the samemanner without necessarily replacing old data. In some embodiments theStored data may be locally stored on the sonar system (e.g., in thestorage module 37 shown in FIG. 2) from a previous trip or pre-loaded onthe device. Additionally or alternatively, the Stored data may belocated on a remote server and sent and/or received via a network (e.g.,the network 56 of FIG. 4). The remote server may be a dedicated externalserver 52 or a third party database 54.

In some embodiments, the Stored data may be outdated or incorrect. Insuch embodiments, the older Stored data may be overwritten by the newerLive data generated by the sonar system 30. In some embodiments, onlyincorrect or different data in the Stored data may be overwritten.Additionally or alternatively, the Stored data may represent lowresolution data and the Live data may be a higher resolution. In suchembodiments, the resolution may be determined by the detail or amount ofdata for a given area. Updating Stored data in such embodiments mayinclude adding additional vertices to a stored 3D mesh data. The lowresolution Stored data may be default data covering a large area ofwater which may not have been previously traveled by the sonar system.In some embodiments the low resolution Stored data may be previouslystored data of the sonar system that was compressed or reduced formemory or network transmission constraints. In such an embodiment, theupdated Stored data may be stored in a higher resolution and either keptin higher resolution (e.g., areas actually traveled by the sonar systemare higher resolution than areas not traveled) or may be later reducedor compressed after a predetermined amount of time, data, or duringtransmission to a remote server.

In some embodiments the Live data may update the Stored data assimultaneously as it is generated (e.g., immediately). In some otherembodiments, the Live data may be cached or temporarily stored beforeupdating the Stored data in bulk (e.g., to conserve processing power ortransmission bandwidth). In embodiments where the Stored data is storedremotely, the sonar system may wait for a wireless signal or networkconnection before uploading the Live data (e.g., the sonar system may beconnected via wireless internet at the end of a journey). The updatingmay be user selectable, such that a user may prompt the Live data toupdate the Stored data, or may prompt the cache to be stored as theStored data.

In some embodiments, a first Stored data may be kept locally and asecond Stored data may be kept remotely. The first and second Storeddata may be simultaneously updated by the Live data. In some alternativeembodiments, one of the first and second Stored data may record a lowresolution version of the Live data and the other may store a highresolution version. In yet some other embodiments, the first Stored datamay be updated as the Live data is generated and the second Stored datamay be updated incrementally, either when a network connection isestablished or when a user prompts the upload.

In some embodiments, the sonar system (e.g., the sonar system 30 of FIG.2) may receive newer Stored data to update the data stored on thedevice. The newer Stored data may be received via the network 56 or viadirect communications with another sonar system or an intermediatestation. In some embodiments, the newer Stored data may be lowresolution data, which may be further updated by Live data as the boattravels. In some embodiments, the user may prompt the sonar system(e.g., via the user interface 42) to download a set of Stored data fromthe network, or alternatively, the sonar system may automaticallyretrieve Stored data based on a direction of travel, GPS route, generalarea, or any other desired factor.

Display and Imaging

In any of the embodiments detailed above, a display (e.g., the display40 of the sonar system 30 shown in FIG. 2) may present one or more setsof data. Combinations of any of the above-referenced sets of data, inaddition to chart information, radar, weather, or any other type ofinformation relevant to watercraft, may be presented simultaneously onthe display (e.g., via split screen). FIGS. 27-28 demonstrate exampleembodiments of such split screen combinations. A user may select any ofthe possible combinations of display, or a sonar system may update thedisplay based on a desired mode or the characteristics of the boat'smotion. For example, the sonar system may automatically add asplit-screen view of a downscan sonar image when a boat is idling or anengine is shut off (e.g., when trolling).

In some further embodiments, various sets of data, referred to above,may be superimposed or overlaid onto one another. For example, the 3Dimage may be applied to a chart information (e.g., a map or navigationalchart). Additionally or alternatively, depth information, weatherinformation, radar information, or any other sonar system inputs may beapplied to one another. For example, weather or radar information may beadded above the boat in the perspective view of the 3D image.

Example System Hardware

In some embodiments, referring back to FIGS. 2-4, the transducerassembly (e.g., the transducer assembly 75 shown in FIG. 6) may includea housing (e.g., the housing 58 shown in FIG. 6) that may includemounting holes through which screws, rivets, bolts or other mountingdevices may be passed in order to fix the housing 58 to a mountingbracket, a device attached to a vessel or to the hull of the vesselitself. However, in some cases, the housing may be affixed by welding,adhesive, snap fit or other coupling means. The housing may be mountedto a portion of the vessel, or to a device attached to the vessel, thatprovides a relatively unobstructed view of both sides of the vessel.Thus, for example, the housing (e.g., the housing 58 shown in FIG. 6)may be mounted on or near the keel (or centerline) of the vessel, on afixed or adjustable mounting bracket that extends below a depth of thekeel (or centerline) of the vessel, or on a mounting device that isoffset from the bow or stern of the vessel (e.g., towfish, trollingmotor, etc.). In some embodiments, the sonar module (e.g., the sonarmodule 44 of FIG. 2) may have one or more components, such as the sonarsignal processor 32, positioned within the housing.

In some embodiments, the transducer array (e.g., transducer arrays 46,48 shown in FIG. 6) may include multiple transducer elements (e.g.,transducer elements 60, 62 shown in FIG. 6). With reference to FIG. 6,the housing 58 may include a recessed portion defining containmentvolume 66 for holding the transducer components. The recessed portiondefining the containment volume may extend away from the hull of thevessel on which the housing 58 is mounted and therefore protrude intothe water on which the vessel operates (or in which the vessel operatesin a case where the transducer assembly is mounted to a tow fish orother submersible device). To prevent cavitation or the production ofbubbles due to uneven flow over the housing 58, the housing 58 (and inparticular the containment volume portion of the housing) may have agradual, rounded or otherwise streamlined profile to permit laminar flowof water over the housing 58. In some examples, an insulated cable mayprovide a conduit for wiring (e.g., transmitter circuitry 71 or receivercircuitry 72) to couple each of the transducer elements 50, 60, 62 tothe sonar module 44. As detailed herein, any of a number ofconfigurations of transducer elements and transducer arrays may beprovided within the housing 58.

The shape of a transducer element may largely determine the type of beamthat is formed when that transducer element transmits a sonar pulse(e.g., a circular transducer element emits a cone-shaped beam, a lineartransducer emits a fan-shaped beam, etc.). In some embodiments, atransducer element may comprise one or more transducer elementspositioned to form one transducer element. For example, a lineartransducer element may comprise two or more rectangular transducerelements aligned with each other so as to be collinear. In someembodiments, three transducer elements aligned in a collinear fashion(e.g., end to end) may define one linear transducer element.

Likewise, transducer elements may comprise different types of materialsthat cause different sonar pulse properties upon transmission. Forexample, the type of material may determine the strength of the sonarpulse. Additionally, the type of material may affect the sonar returnsreceived by the transducer element. As such, embodiments of the presentinvention are not meant to limit the shape or material of the transducerelements. Indeed, while depicted and described embodiments generallydetail a linear transducer element made of piezoelectric material, othershapes and types of material are applicable to embodiments of thepresent invention.

In some embodiments, each of the transducer elements (e.g., transducerelements 50, 60, 62 shown in FIG. 6) may be a linear transducer element.Thus, for example, each of the transducer elements may be substantiallyrectangular in shape and made from a piezoelectric material such as apiezoelectric ceramic material, as is well known in the art. As shown inFIG. 6, the sonar arrays 46, 48 may include an absorptive materialforming mounting slots that hold the transducer elements 60, 62.

As noted above, any of the transducer elements described herein (e.g.,transducer elements 50, 60, 62 shown in FIG. 6) may be configured totransmit and receive sonar pulses (e.g., transmit/receive transducerelements). While the transducer elements may be described herein astransmit/receive transducer elements, in some embodiments, thetransducer elements may be configured as receive-only transducerelements, or in other cases, transmit-only transducer elements.

In transducer elements that transmit, during transmission of sonarpulses, the piezoelectric material, being disposed in a rectangulararrangement, provides for an approximation of a linear array havingbeamwidth characteristics that are a function of the length and width ofthe rectangular face of the transducer elements and the frequency ofoperation. In an example embodiment, a transducer element 50, 60, 62 maybe configured to operate in accordance with at least two operatingfrequencies. In this regard, for example, a frequency selectioncapability may be provided by the sonar module 44 to enable the user toselect one of at least two frequencies of operation. In one example, oneoperating frequency may be set to about 600 kHz and another operatingfrequency may be set to about 480 kHz. Furthermore, the length of thetransducer elements (e.g., transducer elements 50, 60, 62 shown in FIG.6) may be set to about 204 mm (or approximately 8 inches) while thewidth is set to about 1.5 mm to thereby produce beam characteristicscorresponding to a fan of about 0.8 degrees by about 32 degrees at 600kHz or about 1.4 degrees by about 56 degrees at 480 kHz. For example,when operating at 455 kHz, the length and width of the transducerelements may be such that the beamwidth of sonar beam produced by thetransducer elements in a direction parallel to a longitudinal length (L)of the transducer elements is less than about five percent as large asthe beamwidth of the sonar beam in a direction (w) perpendicular to thelongitudinal length of the transducer elements. As such, in someembodiments, any length and width for a transducer element may be used.Lengths longer than 8 inches may be appropriate at operating frequencieslower than those indicated above, and lengths shorter than 8 inches maybe appropriate at frequencies higher than those indicated above.

It should be noted that although the widths of various beams are shownand described herein, the widths being referred to do not necessarilycorrespond to actual edges defining limits to where energy is placed inthe water. As such, although beam patterns and projections of beampatterns are generally shown herein as having fixed and typicallygeometrically shaped and sharply defined boundaries, those boundariesmerely correspond to the −3 dB (or half power) points for thetransmitted beams. In other words, energy measured outside of theboundaries shown is less than half of the energy transmitted, but thissound energy is present nonetheless. Thus, some of the boundaries shownare merely theoretical half power point boundaries.

The transducer elements can convert electrical energy into sound energy(i.e., transmit) and also convert sound energy (e.g., via detectedpressure changes) into an electrical signal (i.e., receive), althoughsome transducers may act only as a hydrophone for converting soundenergy into an electrical signal without operating as a transmitter, oronly operating to convert an electrical signal into sound energy withoutoperating as a receiver. Depending on the desired operation of thetransducer assembly, each of the transducer elements may be configuredto transmit sonar pulses and/or receive sonar returns as desired. Insome embodiments, the transducer assembly 36 may comprise a combinationof transducer elements and/or arrays that are configured to transmitsonar pulses and receive sonar returns, transducer elements that areconfigured to transmit sonar pulses only, and/or transducer elementsthat are configured to receive sonar returns only.

In an example embodiment, the sonar signal processor 32, the transceiver34, the storage module 37 and/or the communications module 38 may form asonar module 44. As such, for example, in some cases, the transducerassembly 36 may simply be placed into communication with the sonarmodule 44, which may itself be a mobile device that may be placed (butnot necessarily mounted in a fixed arrangement) in the vessel to permiteasy installation of one or more displays 40, each of which may beremotely located from each other and operable independent of each other.In this regard, for example, the communications module 38 may includeone or more corresponding interface ports for placing the network incommunication with each display 40 in a plug-n-play manner. As such, forexample, the communications module 38 may not only include the hardwareneeded to enable the displays 40 to be plugged into communication withthe network via the communications module, but the communications module38 may also include or otherwise be in communication with softwaremodules for providing information to enable the sonar module 44 tocommunicate with one or more different instances of the display 40 thatmay or may not be the same model or type of display and that may displaythe same or different information. In other words, the sonar module 44may store configuration settings defining a predefined set of displaytypes with which the sonar module is compatible so that if any of thepredefined set of display types are placed into communication with thesonar module 44, the sonar module 44 may operate in a plug-n-play mannerwith the corresponding display types. Accordingly, the sonar module 44may include the storage device 37 storing device drivers accessible tothe communications module 38 to enable the sonar module 44 to properlywork with displays for which the sonar module 44 is compatible. Thesonar module 44 may also be enabled to be upgraded with additionaldevice drivers or transceivers to enable expansion of the numbers andtypes of devices with which the sonar module 44 may be compatible. Insome cases, the user may select a display type to check whether adisplay type is supported and, if the display type is not supported,contact a network entity to request software and/or drivers for enablingsupport of the corresponding display type.

The sonar signal processor 32 may be any means such as a device orcircuitry operating in accordance with software or otherwise embodied inhardware or a combination of hardware and software (e.g., a processoroperating under software control or the processor embodied as anapplication specific integrated circuit (ASIC) or field programmablegate array (FPGA) specifically configured to perform the operationsdescribed herein, or a combination thereof) thereby configuring thedevice or circuitry to perform the corresponding functions of the sonarsignal processor 32 as described herein. In this regard, the sonarsignal processor 32 may be configured to analyze electrical signalscommunicated thereto by the transceiver 34 to provide sonar dataindicative of the size, location, shape, etc. of objects detected by thesonar system 30. For example, the sonar signal processor 32 may beconfigured to receive sonar return data and process the sonar returndata to generate sonar image data for display to a user (e.g., ondisplay 38). Moreover, in some embodiments, the sonar signal processor32 may be configured to receive downscan sonar return data and sidescansonar return data for processing and generation of sonar image data fordisplay to a user.

In some cases, the sonar signal processor 32 may include a processor, aprocessing element, a coprocessor, a controller or various otherprocessing means or devices including integrated circuits such as, forexample, an ASIC, FPGA or hardware accelerator, that is configured toexecute various programmed operations or instructions stored in a memorydevice. The sonar signal processor 32 may further or alternativelyembody multiple compatible additional hardware or hardware and softwareitems to implement signal processing or enhancement features to improvethe display characteristics or data or images, collect or processadditional data, such as time, temperature, GPS information, waypointdesignations, or others, or may filter extraneous data to better analyzethe collected data. It may further implement notices and alarms, such asthose determined or adjusted by a user, to reflect depth, presence offish, proximity of other watercraft, etc. Still further, the processor,in combination with the storage module 37, may store incoming transducerdata or screen images for future playback or transfer, or alter imageswith additional processing to implement zoom or lateral movement, or tocorrelate data, such as fish or bottom features to a GPS position ortemperature. In an exemplary embodiment, the sonar signal processor 32may execute commercially available software for controlling thetransceiver 34 and/or transducer assembly 36 and for processing datareceived therefrom.

The transceiver 34 may be any means such as a device or circuitryoperating in accordance with software or otherwise embodied in hardwareor a combination of hardware and software (e.g., a processor operatingunder software control or the processor embodied as an ASIC or FPGAspecifically configured to perform the operations described herein, or acombination thereof) thereby configuring the device or circuitry toperform the corresponding functions of the transceiver 34 as describedherein. In this regard, for example, the transceiver 34 may include (orbe in communication with) circuitry (e.g., transmitter circuitry 71shown in FIG. 2) for providing one or more transmission electricalsignals to the transducer assembly 36 for conversion to sound pressuresignals based on the provided electrical signals to be transmitted as asonar pulse. The transceiver 34 may also include (or be in communicationwith) circuitry (e.g., receiver circuitry 72 shown in FIG. 2) forreceiving one or more electrical signals produced by the transducerassembly 36 responsive to sound pressure signals received at thetransducer assembly 36 based on echo or other return signals received inresponse to the transmission of a sonar pulse. The transceiver 34 may bein communication with the sonar signal processor 32 to both receiveinstructions regarding the transmission of sonar signals and to provideinformation on sonar returns to the sonar signal processor 32 foranalysis and ultimately for driving one or more of the displays 38 basedon the sonar returns. In some embodiments, the transmitter circuitry 71and/or receiver circuitry 72 may be positioned within the transceiver 34or sonar module 44. In other embodiments the transmitter circuitry 71and/or receiver circuitry 72 may be positioned within the transducerassembly 36. Likewise, in some embodiments, the transmitter circuitry 71and/or receiver circuitry 72 may be positioned separate from thetransducer assembly 36 and transceiver 34/sonar module 44.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseembodiments of the invention pertain having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is to be understood that the embodiments of the inventionare not to be limited to the specific embodiments disclosed and thatmodifications and other embodiments are intended to be included withinthe scope of the appended claims. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

The invention claimed is:
 1. A sonar system comprising: a housingmountable to a watercraft capable of traversing a body of water; atransmit transducer element positioned within the housing and configuredto transmit sonar pulses into the water; at least one sidescantransducer array positioned within the housing and aimed downwardly andoutwardly from a side of the watercraft, wherein the sidescan transducerarray comprises a first sidescan transducer element and a secondsidescan transducer element, wherein the first sidescan transducerelement is configured to receive first sonar returns from the sonarpulses produced by the transmit transducer element and convert soundenergy of the first sonar returns into first sonar return data, whereinthe second sidescan transducer element is configured to receive secondsonar returns from the sonar pulses produced by the transmit transducerelement and convert sound energy of the second sonar returns into secondsonar return data, and wherein the first sidescan transducer element ispositioned within the housing at a predetermined distance from thesecond sidescan transducer element; and a sonar signal processorconfigured to: process the first sonar return data and the second sonarreturn data to generate a set of 2D sonar data, wherein each sonarreturn of the set of 2D sonar data defines a distance value and anangle, wherein the angle associated with each sonar return is based onthe predetermined distance between the first sidescan transducer elementand the second sidescan transducer element, wherein the distance valueassociated with each sonar return corresponds to a distance between aposition of the sonar return and the at least one sidescan transducerarray; and generate 3D mesh data based on the set of 2D sonar data,wherein the 3D mesh data is a basis for a 3D image of an underwaterenvironment in a three dimensional coordinate system.
 2. The sonarsystem of claim 1, further comprising a display configured to displaythe 3D image of the underwater environment.
 3. The sonar system of claim1, wherein the sonar signal processor is further configured to: generatea plurality of sets of 2D sonar data as the watercraft traverses thebody of water; and generate the 3D mesh data based on the plurality ofsets of 2D sonar data generated as the watercraft traverses the body ofwater.
 4. The sonar system of claim 1, wherein each sonar return of theset of 2D sonar data further defines a signal return strength value. 5.The sonar system of claim 1, wherein the sonar signal processor isfurther configured to process the first sonar return data and the secondsonar return data to generate 2D sonar data by calculating a phasedifference between the first sonar return data and the second sonarreturn data.
 6. The sonar system of claim 1, wherein the sidescantransducer array is a first sidescan transducer array and the side ofthe watercraft is a first side of the watercraft, wherein the sonarsystem further comprises: a second sidescan transducer array positionedwithin the housing and aimed downwardly and outwardly from a second sideof the watercraft, wherein the second side of the watercraft isgenerally opposite to the first side of the watercraft, wherein thesecond sidescan transducer array comprises a third sidescan transducerelement and a fourth sidescan transducer element, wherein the thirdsidescan transducer element is configured to receive third sonar returnsfrom the sonar pulses produced by the transmit transducer element andconvert sound energy of the third sonar returns into third sonar returndata, wherein the fourth sidescan transducer element is configured toreceive fourth sonar returns from the sonar pulses produced by thetransmit transducer element and convert sound energy of the fourth sonarreturns into fourth sonar return data, and wherein the third sidescantransducer element is positioned within the housing at a predetermineddistance from the fourth sidescan transducer element; and wherein thesonar signal processor is further configured to process the third sonarreturn data and the fourth sonar return data to generate the 3D meshdata based on at least the second predetermined distance between thethird sidescan transducer element and the fourth sidescan transducerelement.
 7. The sonar system of claim 1, wherein the predetermineddistance between the first sidescan transducer element and the secondsidescan transducer element defines a first predetermined distance,wherein the sidescan transducer array further comprises a third sidescantransducer element, wherein the third sidescan transducer element isconfigured to receive third sonar returns from the sonar pulses producedby the transmit transducer element and convert sound energy of the thirdsonar returns into third sonar return data, wherein the third sidescantransducer element is positioned a second predetermined distance fromthe second transducer element, and wherein the sonar signal processor isfurther configured to process the first sonar return data, the secondsonar return data, and the third sonar return data to generate the 3Dmesh data based on at least the first predetermined distance and thesecond predetermined distance.
 8. The sonar system of claim 7, whereinthe first predetermined distance between the first sidescan transducerelement and the second sidescan transducer element is different than thesecond predetermined distance between the second sidescan transducerelement and the third sidescan transducer element.
 9. The sonar systemof claim 8, wherein the third sidescan transducer element is positioneda third predetermined distance away from the first sidescan transducerelement, and wherein the sonar signal processor is configured to processthe first sonar return data, the second sonar return data, and the thirdsonar return data to generate the 3D mesh data further based on thethird predetermined distance.
 10. The sonar system of claim 7, whereinthe sidescan transducer array comprises a fourth sidescan transducerelement electrically connected in parallel to the third transducerelement such that the third sidescan transducer element and the fourthsidescan transducer element are configured to act as a single element toreceive the third sonar returns together from the sonar pulses producedby the transmit transducer element and convert the sound energy of thethird sonar returns into the third sonar return data.
 11. The sonarsystem of claim 1, wherein the predetermined distance is designed basedon a frequency of operation of the first sidescan transducer element andsecond sidescan transducer element.
 12. The sonar system of claim 1,wherein the sidescan transducer array defines an emitting surface thatcorresponds to an emitting surface of the first sidescan transducerelement and an emitting surface of the second sidescan transducerelement, wherein the emitting surface is straight such that the emittingsurface of the first sidescan transducer element and the emittingsurface of the second sidescan transducer element are configured todefine the same angle with respect to a surface of the body of water.13. The sonar system of claim 12, wherein the emitting surface of thesidescan transducer array is angled downwardly and outwardly from thewatercraft and substantially perpendicular to a direction of travel ofthe watercraft.
 14. The sonar system of claim 1, wherein the sidescantransducer array defines an emitting surface that corresponds to anemitting surface of the first sidescan transducer element and anemitting surface of the second sidescan transducer element, wherein theemitting surface is curved such that the emitting surface of the firstsidescan transducer element and the emitting surface of the secondsidescan transducer element are configured to define different angleswith respect to a surface of the body of water.
 15. The sonar system ofclaim 1, wherein the transmit transducer element is configured to emit afan-shaped sonar beam having a relatively narrow beamwidth in adirection parallel to a fore-to-aft direction of the watercraft and arelatively wide beamwidth in a direction perpendicular to thefore-to-aft direction of the watercraft.
 16. The sonar system of claim1, wherein the first sidescan transducer element is formed of aplurality of transducer elements electrically connected to act as thefirst sidescan transducer element.
 17. The sonar system of claim 1,wherein the transmit transducer element comprises a linear downscantransducer element positioned within the housing and configured totransmit the sonar pulses in the form of a fan-shaped beam in at least adirection substantially perpendicular to a plane corresponding to asurface of the body of water.
 18. The sonar system of claim 17, whereinthe linear downscan transducer element is formed of a plurality oftransducer elements electrically connected to act as the linear downscantransducer element.
 19. The sonar system of claim 18, wherein: thelinear downscan transducer element is further configured to receivelinear downscan sonar returns from the sonar pulses produced by thelinear downscan transducer element and convert sound energy of thelinear downscan sonar returns into linear downscan sonar return data;the sonar signal processor is further configured to process the lineardownscan sonar return data to generate linear downscan image data; andwherein the sonar system further comprises a display configured todisplay a linear downscan image of the underwater environment based onthe linear downscan image data.
 20. The sonar system of claim 19,wherein the display is configured to display the 3D image of theunderwater environment based on the 3D mesh data and the linear downscanimage of the underwater environment in a split screen format.
 21. Thesonar system of claim 1, further comprising a display configured todisplay the 3D image of the underwater environment based on the 3D meshdata and chart information in a split screen format.
 22. A transducerassembly comprising: a housing mountable to a watercraft capable oftraversing a body of water; a transmit transducer element positionedwithin the housing and configured to transmit sonar pulses into thewater; and at least one sidescan transducer array positioned within thehousing and aimed downwardly and outwardly from a side of thewatercraft, wherein the sidescan transducer array comprises a firstsidescan transducer element and a second sidescan transducer element,wherein the first sidescan transducer element is configured to receivefirst sonar returns from the sonar pulses produced by the transmittransducer element and convert sound energy of the first sonar returnsinto first sonar return data, wherein the second sidescan transducerelement is configured to receive second sonar returns from the sonarpulses produced by the transmit transducer element and convert soundenergy of the second sonar returns into second sonar return data, andwherein the first sidescan transducer element is positioned within thehousing at a predetermined distance from the second sidescan transducerelement; wherein first sonar return data and the second sonar returndata are further configured to define a set of 2D sonar data, whereineach sonar return of the set of 2D sonar data defines a distance valueand an angle, wherein the angle associated with each sonar return isbased on the predetermined distance between the first sidescantransducer element and the second sidescan transducer element, whereinthe distance value associated with each sonar return corresponds to adistance between a position of the sonar return and the at least onesidescan transducer array; wherein the first transducer element andsecond transducer element are configured to transmit the first sonarreturn data and the second sonar return data, respectively, to a sonarsignal processor to be processed by the sonar signal processor togenerate the set of 2D sonar data and 3D mesh data based on the set of2D sonar data, wherein the 3D mesh data is a basis for a 3D image of anunderwater environment in a three dimensional coordinate system.
 23. Thetransducer assembly of claim 22, wherein first sonar return data and thesecond sonar return data are further configured to define a plurality ofsets of 2D sonar data as the watercraft traverses the body of water;such that the first sonar return data and the second sonar return dataare configured to be processed to generate the 3D mesh data based on theplurality of sets of 2D sonar data as the watercraft traverses the bodyof water.
 24. The transducer assembly of claim 22, wherein the firstsonar return data and the second sonar return data are furtherconfigured to define 2D sonar data via a phase difference between thefirst sonar return data and the second sonar return data.
 25. Thetransducer assembly of claim 22, wherein the predetermined distancebetween the first sidescan transducer element and the second sidescantransducer element defines a first predetermined distance, wherein thetransducer assembly further comprises a third sidescan transducerelement, wherein the third sidescan transducer element is configured toreceive third sonar returns from the sonar pulses produced by thetransmit transducer element and convert sound energy of the third sonarreturns into third sonar return data, wherein the third sidescantransducer element is positioned a second predetermined distance fromthe second transducer element, and wherein the first sonar return data,the second sonar return data, and the third sonar return data areconfigured to be processed to generate the 3D mesh data based on atleast the first predetermined distance and the second predetermineddistance.
 26. The transducer assembly of claim 25, wherein the firstpredetermined distance between the first sidescan transducer element andthe second sidescan transducer element is different than the secondpredetermined distance between the second sidescan transducer elementand the third sidescan transducer element.
 27. The transducer assemblyof claim 25, wherein the third sidescan transducer element is positioneda third predetermined distance away from the first sidescan transducerelement, and wherein the first sonar return data, the second sonarreturn data, and the third sonar return data are configured to beprocessed to generate the 3D mesh data further based on the thirdpredetermined distance.
 28. The transducer assembly of claim 25, whereinthe sidescan transducer array comprises a fourth sidescan transducerelement electrically connected in parallel to the third transducerelement such that the third sidescan transducer element and the fourthsidescan transducer element are configured to act as a single element toreceive the third sonar returns together from the sonar pulses producedby the transmit transducer element and convert the sound energy of thethird sonar returns into the third sonar return data.
 29. The transducerassembly of claim 22, wherein transmit transducer element is configuredto emit a fan-shaped sonar beam having a relatively narrow beamwidth ina direction parallel to a fore-to-aft direction of the watercraft and arelatively wide beamwidth in a direction perpendicular to thefore-to-aft direction of the watercraft.
 30. A method for imaging anunderwater environment comprising: transmitting sonar pulses into a bodyof water using a transmit transducer element positioned within a housingmountable to a watercraft capable of traversing the body of water;receiving, via a first sidescan transducer element of a sidescantransducer array, first sonar returns from the sonar pulses produced bythe transmit transducer element, wherein the sidescan, transducer arrayis positioned within the housing and aimed downwardly and outwardly froma side of the watercraft, and wherein the first sidescan transducerelement is configured to convert sound energy of the first sonar returnsinto first sonar return data; receiving, via a second sidescantransducer element of the sidescan transducer array, second sonarreturns from the sonar pulses produced by the transmit transducerelement, wherein the second sidescan transducer element is configured toconvert sound energy of the second sonar returns into second sonarreturn data, and wherein the first sidescan transducer element ispositioned within the housing at a predetermined distance from thesecond sidescan transducer element; and processing, via a sonar signalprocessor, the first sonar return data and the second sonar return datato generate a set of 2D sonar data, wherein each sonar return of the setof 2D sonar data defines a distance value and an angle, wherein theangle associated with each sonar return is based on the predetermineddistance between the first sidescan transducer element and the secondsidescan transducer element, wherein the distance value associated witheach sonar return corresponds to a distance between a position of thesonar return and the at least one sidescan transducer array; andgenerating 3D mesh data based on the set of 2D sonar data, wherein the3D mesh data is a basis for a 3D image of an underwater environment in athree dimensional coordinate system.
 31. The method of claim 30, furthercomprising displaying, via a display, the 3D image of the underwaterenvironment.
 32. The method of claim 30, wherein processing the firstsonar return data and the second sonar return data further comprises:generating a plurality of sets of 2D sonar data as the watercrafttraverses the body of water; and generating the 3D mesh data based onthe plurality of sets of 2D sonar data generated as the watercrafttraverses the body of water.
 33. The method of claim 30, whereinprocessing the first sonar return data and the second sonar return datato generate 2D sonar data comprises calculating, based on at least thepredetermined distance, a phase difference between the first sonarreturn data and the second sonar return data.
 34. A sonar systemcomprising: a housing mountable to a watercraft capable of traversing abody of water; at least one sidescan transducer array positioned withinthe housing and aimed downwardly and outwardly from a side of thewatercraft, wherein the sidescan transducer array comprises a firstsidescan transducer element and a second sidescan transducer element,wherein the first sidescan transducer element is configured to transmitsonar pulses into the water, receive first sonar returns from the sonarpulses produced by the first sidescan transducer element, and convertsound energy of the first sonar returns into first sonar return data,wherein the second sidescan transducer element is configured to receivesecond sonar returns from the sonar pulses produced by the firstsidescan transducer element and convert sound energy of the second sonarreturns into second sonar return data, and wherein the first sidescantransducer element is positioned within the housing at a predetermineddistance from the second sidescan transducer element; and a sonar signalprocessor configured to: process the first sonar return data and thesecond sonar return data to generate a set of 2D sonar data, whereineach sonar return of the set of 2D sonar data defines a distance valueand an angle, wherein the angle associated with each sonar return isbased on the predetermined distance between the first sidescantransducer element and the second sidescan transducer element, whereinthe distance value associated with each sonar return corresponds to adistance between a position of the sonar return and the at least onesidescan transducer array; and generate 3D mesh data based on the set of2D sonar data, wherein the 3D mesh data is a basis for a 3D image of anunderwater environment in a three dimensional coordinate system.
 35. Thesonar system of claim 34, further comprising a display configured todisplay the image of the underwater environment.
 36. The sonar system ofclaim 34, wherein the sonar signal processor is further configured to:generate a plurality of sets of 2D sonar data as the watercraft traversethe body of water; and generate the 3D mesh data based on the pluralityof sets of 2D sonar data generated as the watercraft traverses the bodyof water.